Issue summary: When a partial-chain certificate verification is enabled together with OCSP response checking for the whole chain, a NULL dereference will happen if the verified chain does not have a self-signed trusted anchor, crashing the process. Impact summary: A NULL pointer dereference can trigger a crash which leads to a Denial of Service for an application. When performing OCSP response checking for certificates in the verification chain, the code always tries to access the next certificate as the issuer. There is a check for a self-signed certificate. However with the partial chain verification enabled when the chain does not have a self-signed trusted anchor, the issuer will be NULL for the last certificate in the chain. A NULL pointer dereference then happens. This issue affects only applications which enable both OCSP verification of the certificate chain (X509_V_FLAG_OCSP_RESP_CHECK_ALL) and partial chain verification (X509_V_FLAG_PARTIAL_CHAIN) in the certificate verification. Both flags are disabled by default. For that reason, we have assigned Low severity to the issue. No FIPS modules are affected by this issue as the affected code is outside the OpenSSL FIPS module boundary.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Issue summary: When a partial-chain certificate verification is enabled together with OCSP response     checking for the whole chain, a NULL dereference will happen if the verified chain does not have a self-     signed trusted anchor, crashing the process. Impact summary: A NULL pointer dereference can trigger a     crash which leads to a Denial of Service for an application. When performing OCSP response checking for     certificates in the verification chain, the code always tries to access the next certificate as the     issuer. There is a check for a self-signed certificate. However with the partial chain verification     enabled when the chain does not have a self-signed trusted anchor, the issuer will be NULL for the last     certificate in the chain. A NULL pointer dereference then happens. This issue affects only applications     which enable both OCSP verification of the certificate chain (X509_V_FLAG_OCSP_RESP_CHECK_ALL) and partial     chain verification (X509_V_FLAG_PARTIAL_CHAIN) in the certificate verification. Both flags are disabled by     default. For that reason, we have assigned Low severity to the issue. No FIPS modules are affected by this     issue as the affected code is outside the OpenSSL FIPS module boundary. (CVE-2026-42765)

Note that Nessus relies on the presence of the package as reported by the vendor.

The version of OpenSSL installed on the remote host is prior to 4.0.1. It is, therefore, affected by multiple vulnerabilities as referenced in the 4.0.1 advisory.

  - Issue summary: A specially crafted PKCS#7 or S/MIME signed message could trigger a use-after-free during     PKCS#7 signature verification. Impact summary: A use-after-free may result in process crashes, heap     corruption, or potentially remote code execution. When processing a PKCS#7 or S/MIME signed message, if     the SignedData digestAlgorithms field is present as an empty ASN.1 SET, OpenSSL may incorrectly free a     caller-owned BIO during PKCS7_verify(). A subsequent use of the BIO by the calling application results in     a use-after-free condition. In the common case this occurs when the application later calls BIO_free() on     the BIO originally passed to PKCS7_verify(). Depending on allocator behavior and application-specific BIO     usage patterns, this may result in a crash or other memory corruption. In some application contexts this     may potentially be exploitable for remote code execution. Applications that process PKCS#7 or S/MIME     signed messages using OpenSSL PKCS#7 APIs may be affected. Applications using the CMS APIs for this     processing are not affected. The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this     issue, as the affected code is outside the OpenSSL FIPS module boundary. (CVE-2026-45447)

  - Issue summary: When CMS password-based decryption (RFC 3211 / PWRI key unwrap) processes attacker-supplied     CMS data, an attacker-chosen stream-mode KEK cipher can trigger a heap out-of-bounds read in     kek_unwrap_key(). Impact summary: A heap buffer over-read may trigger a crash which leads to Denial of     Service for an application if the input buffer ends at a memory page boundary and the following page is     unmapped. There is no information disclosure as the over-read bytes are not revealed to the attacker. The     key unwrapping function performs a check-byte test as specified in the RFC that reads 7 bytes from a heap     allocation that is based on the wrapped key length from the message. There is a minimum length check based     on the block length of the wrapping cipher. However the cipher is selected from an OID carried in the     attacker's PWRI keyEncryptionAlgorithm with no requirement that the cipher be a block cipher. When an     attacker selects a stream-mode cipher the guard will be ineffective and the allocated buffer containing     the unwrapped key can be too small to fit the check-bytes specified in the RFC and a buffer over-read can     happen. Applications calling CMS_decrypt() or CMS_decrypt_set1_password() (equivalently openssl cms
    -decrypt -pwri_password ...) on untrusted CMS data are vulnerable to this issue. No password knowledge is     required: the over-read happens during the unwrap attempt before any authentication succeeds. The over-     read is limited to a few bytes and is not written to output, so there is no information disclosure.
    Triggering a crash requires the allocation to border unmapped memory, which is unlikely with the normal     allocator. The FIPS modules are not affected by this issue. (CVE-2026-9076)

  - Issue summary: A signed integer overflow when sizing the destination buffer for Unicode output in     ASN1_mbstring_ncopy() can lead to a heap buffer overflow. Impact summary: A heap buffer overflow may lead     to a crash or possibly attacker controlled code execution or other undefined behaviour. In     ASN1_mbstring_copy() and ASN1_mbstring_ncopy() the destination size for Unicode output is computed in a     signed int: by left shift of the input character count for BMPSTRING (UTF-16) and UNIVERSALSTRING     (UTF-32), and by summing per-character byte counts for UTF8STRING. The calculation overflows when the     input reaches around 2^30 characters. In the worst case (UNIVERSALSTRING at 2^30 characters) the size     wraps to zero, OPENSSL_malloc(1) is called, and the subsequent character copy writes several gigabytes     past the one-byte allocation. X.509 certificate processing routes through ASN1_STRING_set_by_NID(), whose     DIRSTRING_TYPE mask excludes UNIVERSALSTRING and whose per-NID size limits cap the input length; no     network protocol or certificate-handling path in OpenSSL exercises the overflow. Triggering the bug     requires an application that calls ASN1_mbstring_copy() or ASN1_mbstring_ncopy() directly, or registers a     custom string type via ASN1_STRING_TABLE_add(), with attacker-controlled input on the order of half a     gigabyte or more. For these reasons this issue was assigned Low severity. The FIPS modules in 4.0, 3.6,     3.5, 3.4 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module     boundary. (CVE-2026-7383)

  - Issue summary: The implementations of AES-SIV (RFC 5297) and AES-GCM-SIV (RFC 8452) mishandle the     authentication of AAD (Additional Authenticated Data) with an empty ciphertext allowing a forgery of such     messages. Impact summary: An attacker can forge empty messages with arbitrary AAD to the victim's     application using these ciphers. AES-SIV (RFC 5297) and AES-GCM-SIV (RFC 8452) are nonce-misuse-resistant     AEAD modes: they accept a key, nonce, optional AAD (bytes that are authenticated but not encrypted), and     plaintext, and produces ciphertext plus a 16-byte tag. On decrypt, `EVP_DecryptFinal_ex()` is documented     to return success only if the tag is verified succesfully. In OpenSSL's provider implementation of these     ciphers, the expected tag is computed only when decryption function is invoked with non-empty data. If the     caller supplies AAD and then calls `EVP_DecryptFinal_ex()` without invocation of the ciphertext update,     which can happen when the received ciphertext length is zero, the tag is never recalculated and still     holds its all-zeros value. When AES-GCM-SIV is used, an attacker who sends arbitrary AAD, empty     ciphertext, and all-zeros tag passes authentication under any key they do not know, single-shot. When AES-     SIV is used, for mounting the attack it's necessary for the application to reuse the decryption context     without resetting the key. AES-SIV is implemented since OpenSSL 3.0. AES-GCM-SIV is implemented since     OpenSSL 3.2. No protocols implemented in OpenSSL itself (TLS/CMS/PKCS7/HPKE/QUIC) support either AES-GCM-     SIV or AES-SIV. To mount an attack, the applications must implement their own protocol and use the EVP     interface. Also they must skip the ciphertext update when a message with an empty ciphertext arrives. The     FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as these algorithms are not     FIPS approved and the affected code is outside the OpenSSL FIPS module boundary. (CVE-2026-45446)

  - Issue summary: When an application drives an AES-OCB context through the public EVP_Cipher() one-shot     interface, the application-supplied initialisation vector (IV) is silently discarded. Impact summary:
    Every message encrypted under the same key uses the same effective nonce regardless of the IV supplied by     the caller, resulting in (key, nonce) reuse and loss of confidentiality. If the same code path is used to     compute the authentication tag, the tag depends only on the (key, IV) pair and not on the plaintext or     ciphertext, allowing universal forgery of arbitrary ciphertext from a single captured message. OpenSSL     provides two ways to drive a cipher: the documented streaming interface (EVP_CipherUpdate /     EVP_CipherFinal_ex) and a lower-level one-shot, EVP_Cipher(), whose documentation explicitly recommends     against use by applications in favour of EVP_CipherUpdate() and EVP_CipherFinal_ex(). The OCB provider's     streaming handler flushes the application-supplied IV into the OCB context before processing data; the     one-shot handler did not. Every call to EVP_Cipher() on an AES-OCB context therefore ran with the all-zero     key-derived offset state left by cipher initialisation, regardless of the caller's IV. If     EVP_EncryptFinal_ex() is subsequently used to obtain the authentication tag, the deferred IV setup runs at     that point and clears the running checksum that should have been accumulated over the plaintext. The     resulting tag is a function of (key, IV) only and verifies against any ciphertext produced under the same     (key, IV) pair. The OpenSSL SSL/TLS implementation is not affected: AES-OCB is not a TLS cipher suite, and     libssl does not call EVP_Cipher() in any case. Applications that drive AES-OCB through the documented     streaming AEAD API (EVP_CipherUpdate / EVP_CipherFinal_ex) are not affected. Only applications that     combine the AES-OCB cipher with the EVP_Cipher() one-shot API are vulnerable. The FIPS modules in 4.0,     3.6, 3.5, 3.4 and 3.0 are not affected by this issue, as AES-OCB is outside the OpenSSL FIPS module     boundary. (CVE-2026-45445)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The version of OpenSSL installed on the remote host is prior to 3.6.3. It is, therefore, affected by multiple vulnerabilities as referenced in the 3.6.3 advisory.

  - Issue summary: A specially crafted PKCS#7 or S/MIME signed message could trigger a use-after-free during     PKCS#7 signature verification. Impact summary: A use-after-free may result in process crashes, heap     corruption, or potentially remote code execution. When processing a PKCS#7 or S/MIME signed message, if     the SignedData digestAlgorithms field is present as an empty ASN.1 SET, OpenSSL may incorrectly free a     caller-owned BIO during PKCS7_verify(). A subsequent use of the BIO by the calling application results in     a use-after-free condition. In the common case this occurs when the application later calls BIO_free() on     the BIO originally passed to PKCS7_verify(). Depending on allocator behavior and application-specific BIO     usage patterns, this may result in a crash or other memory corruption. In some application contexts this     may potentially be exploitable for remote code execution. Applications that process PKCS#7 or S/MIME     signed messages using OpenSSL PKCS#7 APIs may be affected. Applications using the CMS APIs for this     processing are not affected. The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this     issue, as the affected code is outside the OpenSSL FIPS module boundary. (CVE-2026-45447)

  - Issue summary: When CMS password-based decryption (RFC 3211 / PWRI key unwrap) processes attacker-supplied     CMS data, an attacker-chosen stream-mode KEK cipher can trigger a heap out-of-bounds read in     kek_unwrap_key(). Impact summary: A heap buffer over-read may trigger a crash which leads to Denial of     Service for an application if the input buffer ends at a memory page boundary and the following page is     unmapped. There is no information disclosure as the over-read bytes are not revealed to the attacker. The     key unwrapping function performs a check-byte test as specified in the RFC that reads 7 bytes from a heap     allocation that is based on the wrapped key length from the message. There is a minimum length check based     on the block length of the wrapping cipher. However the cipher is selected from an OID carried in the     attacker's PWRI keyEncryptionAlgorithm with no requirement that the cipher be a block cipher. When an     attacker selects a stream-mode cipher the guard will be ineffective and the allocated buffer containing     the unwrapped key can be too small to fit the check-bytes specified in the RFC and a buffer over-read can     happen. Applications calling CMS_decrypt() or CMS_decrypt_set1_password() (equivalently openssl cms
    -decrypt -pwri_password ...) on untrusted CMS data are vulnerable to this issue. No password knowledge is     required: the over-read happens during the unwrap attempt before any authentication succeeds. The over-     read is limited to a few bytes and is not written to output, so there is no information disclosure.
    Triggering a crash requires the allocation to border unmapped memory, which is unlikely with the normal     allocator. The FIPS modules are not affected by this issue. (CVE-2026-9076)

  - Issue summary: A signed integer overflow when sizing the destination buffer for Unicode output in     ASN1_mbstring_ncopy() can lead to a heap buffer overflow. Impact summary: A heap buffer overflow may lead     to a crash or possibly attacker controlled code execution or other undefined behaviour. In     ASN1_mbstring_copy() and ASN1_mbstring_ncopy() the destination size for Unicode output is computed in a     signed int: by left shift of the input character count for BMPSTRING (UTF-16) and UNIVERSALSTRING     (UTF-32), and by summing per-character byte counts for UTF8STRING. The calculation overflows when the     input reaches around 2^30 characters. In the worst case (UNIVERSALSTRING at 2^30 characters) the size     wraps to zero, OPENSSL_malloc(1) is called, and the subsequent character copy writes several gigabytes     past the one-byte allocation. X.509 certificate processing routes through ASN1_STRING_set_by_NID(), whose     DIRSTRING_TYPE mask excludes UNIVERSALSTRING and whose per-NID size limits cap the input length; no     network protocol or certificate-handling path in OpenSSL exercises the overflow. Triggering the bug     requires an application that calls ASN1_mbstring_copy() or ASN1_mbstring_ncopy() directly, or registers a     custom string type via ASN1_STRING_TABLE_add(), with attacker-controlled input on the order of half a     gigabyte or more. For these reasons this issue was assigned Low severity. The FIPS modules in 4.0, 3.6,     3.5, 3.4 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module     boundary. (CVE-2026-7383)

  - Issue summary: The implementations of AES-SIV (RFC 5297) and AES-GCM-SIV (RFC 8452) mishandle the     authentication of AAD (Additional Authenticated Data) with an empty ciphertext allowing a forgery of such     messages. Impact summary: An attacker can forge empty messages with arbitrary AAD to the victim's     application using these ciphers. AES-SIV (RFC 5297) and AES-GCM-SIV (RFC 8452) are nonce-misuse-resistant     AEAD modes: they accept a key, nonce, optional AAD (bytes that are authenticated but not encrypted), and     plaintext, and produces ciphertext plus a 16-byte tag. On decrypt, `EVP_DecryptFinal_ex()` is documented     to return success only if the tag is verified succesfully. In OpenSSL's provider implementation of these     ciphers, the expected tag is computed only when decryption function is invoked with non-empty data. If the     caller supplies AAD and then calls `EVP_DecryptFinal_ex()` without invocation of the ciphertext update,     which can happen when the received ciphertext length is zero, the tag is never recalculated and still     holds its all-zeros value. When AES-GCM-SIV is used, an attacker who sends arbitrary AAD, empty     ciphertext, and all-zeros tag passes authentication under any key they do not know, single-shot. When AES-     SIV is used, for mounting the attack it's necessary for the application to reuse the decryption context     without resetting the key. AES-SIV is implemented since OpenSSL 3.0. AES-GCM-SIV is implemented since     OpenSSL 3.2. No protocols implemented in OpenSSL itself (TLS/CMS/PKCS7/HPKE/QUIC) support either AES-GCM-     SIV or AES-SIV. To mount an attack, the applications must implement their own protocol and use the EVP     interface. Also they must skip the ciphertext update when a message with an empty ciphertext arrives. The     FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this issue, as these algorithms are not     FIPS approved and the affected code is outside the OpenSSL FIPS module boundary. (CVE-2026-45446)

  - Issue summary: When an application drives an AES-OCB context through the public EVP_Cipher() one-shot     interface, the application-supplied initialisation vector (IV) is silently discarded. Impact summary:
    Every message encrypted under the same key uses the same effective nonce regardless of the IV supplied by     the caller, resulting in (key, nonce) reuse and loss of confidentiality. If the same code path is used to     compute the authentication tag, the tag depends only on the (key, IV) pair and not on the plaintext or     ciphertext, allowing universal forgery of arbitrary ciphertext from a single captured message. OpenSSL     provides two ways to drive a cipher: the documented streaming interface (EVP_CipherUpdate /     EVP_CipherFinal_ex) and a lower-level one-shot, EVP_Cipher(), whose documentation explicitly recommends     against use by applications in favour of EVP_CipherUpdate() and EVP_CipherFinal_ex(). The OCB provider's     streaming handler flushes the application-supplied IV into the OCB context before processing data; the     one-shot handler did not. Every call to EVP_Cipher() on an AES-OCB context therefore ran with the all-zero     key-derived offset state left by cipher initialisation, regardless of the caller's IV. If     EVP_EncryptFinal_ex() is subsequently used to obtain the authentication tag, the deferred IV setup runs at     that point and clears the running checksum that should have been accumulated over the plaintext. The     resulting tag is a function of (key, IV) only and verifies against any ciphertext produced under the same     (key, IV) pair. The OpenSSL SSL/TLS implementation is not affected: AES-OCB is not a TLS cipher suite, and     libssl does not call EVP_Cipher() in any case. Applications that drive AES-OCB through the documented     streaming AEAD API (EVP_CipherUpdate / EVP_CipherFinal_ex) are not affected. Only applications that     combine the AES-OCB cipher with the EVP_Cipher() one-shot API are vulnerable. The FIPS modules in 4.0,     3.6, 3.5, 3.4 and 3.0 are not affected by this issue, as AES-OCB is outside the OpenSSL FIPS module     boundary. (CVE-2026-45445)

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Severity
320332	Linux Distros Unpatched Vulnerability : CVE-2026-42765	Nessus	Misc.	high
320140	OpenSSL 4.0.0 < 4.0.1 Multiple Vulnerabilities	Nessus	Web Servers	critical
320135	OpenSSL 3.6.0 < 3.6.3 Multiple Vulnerabilities	Nessus	Web Servers	critical

Detections

Analytics

CVE-2026-42765

high

Tenable Plugins

high

critical

critical