Issue summary: Applications using AES-CFB128 encryption or decryption on systems with AVX-512 and VAES support can trigger an out-of-bounds read of up to 15 bytes when processing partial cipher blocks. Impact summary: This out-of-bounds 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 written to output. The vulnerable code path is only reached when processing partial blocks (when a previous call left an incomplete block and the current call provides fewer bytes than needed to complete it). Additionally, the input buffer must be positioned at a page boundary with the following page unmapped. CFB mode is not used in TLS/DTLS protocols, which use CBC, GCM, CCM, or ChaCha20-Poly1305 instead. For these reasons the issue was assessed as Low severity according to our Security Policy. Only x86-64 systems with AVX-512 and VAES instruction support are affected. Other architectures and systems without VAES support use different code paths that are not affected. OpenSSL FIPS module in 3.6 version is affected by this issue.

The version of FreeBSD installed on the remote host is prior to tested version. It is, therefore, affected by multiple vulnerabilities as referenced in the c7a52cee-32ab-11f1-9839-8447094a420f advisory.

    The OpenSSL project reports:
    Seven vulnerabilities in OpenSSL library. Highest classification Moderate.

Tenable has extracted the preceding description block directly from the FreeBSD security advisory.

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

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

  - Issue summary: Applications using AES-CFB128 encryption or decryption on systems with AVX-512 and VAES     support can trigger an out-of-bounds read of up to 15 bytes when processing partial cipher blocks. Impact     summary: This out-of-bounds 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 written to output. The vulnerable code path is only     reached when processing partial blocks (when a previous call left an incomplete block and the current call     provides fewer bytes than needed to complete it). Additionally, the input buffer must be positioned at a     page boundary with the following page unmapped. CFB mode is not used in TLS/DTLS protocols, which use CBC,     GCM, CCM, or ChaCha20-Poly1305 instead. For these reasons the issue was assessed as Low severity according     to our Security Policy. Only x86-64 systems with AVX-512 and VAES instruction support are affected. Other     architectures and systems without VAES support use different code paths that are not affected. OpenSSL     FIPS module in 3.6 version is affected by this issue. (CVE-2026-28386)

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 3.6.2. It is, therefore, affected by multiple vulnerabilities as referenced in the 3.6.2 advisory.

  - Issue summary: An OpenSSL TLS 1.3 server may fail to negotiate the expected preferred key exchange group     when its key exchange group configuration includes the default by using the 'DEFAULT' keyword. Impact     summary: A less preferred key exchange may be used even when a more preferred group is supported by both     client and server, if the group was not included among the client's initial predicated keyshares. This     will sometimes be the case with the new hybrid post-quantum groups, if the client chooses to defer their     use until specifically requested by the server. If an OpenSSL TLS 1.3 server's configuration uses the     'DEFAULT' keyword to interpolate the built-in default group list into its own configuration, perhaps     adding or removing specific elements, then an implementation defect causes the 'DEFAULT' list to lose its     'tuple' structure, and all server-supported groups were treated as a single sufficiently secure 'tuple',     with the server not sending a Hello Retry Request (HRR) even when a group in a more preferred tuple was     mutually supported. As a result, the client and server might fail to negotiate a mutually supported post-     quantum key agreement group, such as 'X25519MLKEM768', if the client's configuration results in only     'classical' groups (such as 'X25519' being the only ones in the client's initial keyshare prediction).
    OpenSSL 3.5 and later support a new syntax for selecting the most preferred TLS 1.3 key agreement group on     TLS servers. The old syntax had a single 'flat' list of groups, and treated all the supported groups as     sufficiently secure. If any of the keyshares predicted by the client were supported by the server the most     preferred among these was selected, even if other groups supported by the client, but not included in the     list of predicted keyshares would have been more preferred, if included. The new syntax partitions the     groups into distinct 'tuples' of roughly equivalent security. Within each tuple the most preferred group     included among the client's predicted keyshares is chosen, but if the client supports a group from a more     preferred tuple, but did not predict any corresponding keyshares, the server will ask the client to retry     the ClientHello (by issuing a Hello Retry Request or HRR) with the most preferred mutually supported     group. The above works as expected when the server's configuration uses the built-in default group list,     or explicitly defines its own list by directly defining the various desired groups and group 'tuples'. No     OpenSSL FIPS modules are affected by this issue, the code in question lies outside the FIPS boundary.
    OpenSSL 3.6 and 3.5 are vulnerable to this issue. OpenSSL 3.6 users should upgrade to OpenSSL 3.6.2 once     it is released. OpenSSL 3.5 users should upgrade to OpenSSL 3.5.6 once it is released. OpenSSL 3.4, 3.3,     3.0, 1.0.2 and 1.1.1 are not affected by this issue. (CVE-2026-2673)

  - Debian Linux - openssl - None  Red Hat Enterprise Linux - openssl: openssl: Information Disclosure from     Uninitialized Memory via Invalid RSA Public Key (CVE-2026-31790)

  - Debian Linux - openssl - None (CVE-2026-28389, CVE-2026-28390, CVE-2026-31789)

  - Issue summary: When a delta CRL that contains a Delta CRL Indicator extension is processed a NULL pointer     dereference might happen if the required CRL Number extension is missing.  Impact summary: A NULL pointer     dereference can trigger a crash which leads to a Denial of Service for an application.  When CRL     processing and delta CRL processing is enabled during X.509 certificate verification, the delta CRL     processing does not check whether the CRL Number extension is NULL before dereferencing it. When a     malformed delta CRL file is being processed, this parameter can be NULL, causing a NULL pointer     dereference.  Exploiting this issue requires the X509_V_FLAG_USE_DELTAS flag to be enabled in the     verification context, the certificate being verified to contain a freshestCRL extension or the base CRL to     have the EXFLAG_FRESHEST flag set, and an attacker to provide a malformed CRL to an application that     processes it.  The vulnerability is limited to Denial of Service and cannot be escalated to achieve code     execution or memory disclosure. For that reason the issue was assessed as Low severity according to our     Security Policy.  The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the     affected code is outside the OpenSSL FIPS module boundary. Fixed in OpenSSL 3.6.2 (Affected since 3.6.0).
    (CVE-2026-28388)

  - Issue summary: An uncommon configuration of clients performing DANE TLSA-based server authentication, when     paired with uncommon server DANE TLSA records, may result in a use-after-free and/or double-free on the     client side.  Impact summary: A use after free can have a range of potential consequences such as the     corruption of valid data, crashes or execution of arbitrary code.  However, the issue only affects clients     that make use of TLSA records with both the PKIX-TA(0/PKIX-EE(1) certificate usages and the DANE-TA(2)     certificate usage.  By far the most common deployment of DANE is in SMTP MTAs for which RFC7672 recommends     that clients treat as 'unusable' any TLSA records that have the PKIX certificate usages.  These SMTP (or     other similar) clients are not vulnerable to this issue.  Conversely, any clients that support only the     PKIX usages, and ignore the DANE-TA(2) usage are also not vulnerable.  The client would also need to be     communicating with a server that publishes a TLSA RRset with both types of TLSA records.  No FIPS modules     are affected by this issue, the problem code is outside the FIPS module boundary. Fixed in OpenSSL 3.6.2     (Affected since 3.6.0). (CVE-2026-28387)

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
305290	FreeBSD : OpenSSL -- Multiple vulnerabilities (c7a52cee-32ab-11f1-9839-8447094a420f)	Nessus	FreeBSD Local Security Checks	high
305211	Linux Distros Unpatched Vulnerability : CVE-2026-28386	Nessus	Misc.	critical
302501	OpenSSL 3.6.0 < 3.6.2 Multiple Vulnerabilities	Nessus	Web Servers	high

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CVE-2026-28386

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