Libreswan in FIPS mode has a vulnerability where badly formed received certificates are rejected, but not deleted from the NSS cache. As a result, any real certificates with the same serial number are rejected as well. This can be abused to lock out legitimate peers from connecting. The add_decoded_cert() function missed a call to CERT_DestroyCertificate() due to an incorrect fix for CVE-2026-14957. Sending bogus certificates with new serial numbers could prevent the real certificates with those serial numbers from connecting until the service has restarted.

The remote Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-fe33d29b75 advisory.

    Fixes CVE-2026-77205, CVE-2026-77206, CVE-2026-77207 and CVE-2026-9445

Tenable has extracted the preceding description block directly from the Fedora 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 Rocky Linux 10.2 host has packages installed that are affected by multiple vulnerabilities as referenced in the CIQ crlsa-2026_89923 advisory.

    * libreswan: IKEv2 Use-After-Free bug when using IKE-over-TCP (CVE-2026-94453)

    * libreswan: Denial of Service via sending bogus X.509 certificates (CVE-2026-77205)

    * libreswan: Null Pointer Dereference in PKCS#7 bundle with no CERTS (CVE-2026-77207)

Tenable has extracted the preceding description block directly from the CIQ 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 remote Fedora 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-92b72db5d7 advisory.

    Fixes CVE-2026-77205, CVE-2026-77206, CVE-2026-77207 and CVE-2026-9445

Tenable has extracted the preceding description block directly from the Fedora 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 remote RockyLinux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the RLSA-2026:89923 advisory.

    * libreswan: IKEv2 Use-After-Free bug when using IKE-over-TCP (CVE-2026-94453)

    * libreswan: Denial of Service via sending bogus X.509 certificates (CVE-2026-77205)

    * libreswan: Null Pointer Dereference in PKCS#7 bundle with no CERTS (CVE-2026-77207)

Tenable has extracted the preceding description block directly from the RockyLinux 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 remote Oracle Linux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the ELSA-2026-89923 advisory.

    [5.3.3-1.0.1]
    - Add libreswan-oracle.patch to detect Oracle Linux distro

    [5.3.3-1]
    - update to 5.3.3 to fix CVE-2026-94453, CVE-2026-77207, CVE-2026-77205, and CVE-2026-77206

Tenable has extracted the preceding description block directly from the Oracle Linux 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 remote Redhat Enterprise Linux 10 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:89923 advisory.

    Libreswan is an implementation of IPsec and IKE for Linux. IPsec is the Internet Protocol Security and     uses strong cryptography to provide both authentication and encryption services. These services allow you     to build secure tunnels through untrusted networks such as virtual private network (VPN).

    Security Fix(es):

    * libreswan: IKEv2 Use-After-Free bug when using IKE-over-TCP (CVE-2026-94453)

    * libreswan: Denial of Service via sending bogus X.509 certificates (CVE-2026-77205)

    * libreswan: Null Pointer Dereference in PKCS#7 bundle with no CERTS (CVE-2026-77207)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux 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.

  - Libreswan in FIPS mode has a vulnerability where badly formed received certificates are rejected, but not     deleted from the NSS cache. As a result, any real certificates with the same serial number are rejected as     well. This can be abused to lock out legitimate peers from connecting. The add_decoded_cert() function     missed a call to CERT_DestroyCertificate() due to an incorrect fix for CVE-2026-14957. Sending bogus     certificates with new serial numbers could prevent the real certificates with those serial numbers from     connecting until the service has restarted. (CVE-2026-77205)

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

There are packages installed that are affected by multiple vulnerabilities referenced in the following CVEs:

  - Libreswan, via the function RSA_authenticate_hash_signature_pkcs1_1_5_rsa(), did not correctly verify the
    DER encoding of the ASN.1 digest when the IKEv2 AUTH payload was encoded using RSASSA-PKCS1-v1_5 (RFC
    8017). A remote attacker can use a variation on the Bleichenbacher attack to forge the AUTH payload when
    small public exponents are used (e.g., e=3), leading to impersonation. Additionally, a remote attacker, by
    encoding a shorter than expected hash in the AUTH payload, could trigger an assertion leading to denial-
    of-service. The daemon aborts and restarts; continued exploitation causes sustained denial of service.
    Remote code execution is not possible. X.509 certificate verifications of the remote IKE peer are not
    affected. (CVE-2026-50722)

  - An invalidly formatted IKEv2 fragment causes the Libreswan pluto daemon to crash and restart. Continued
    exploitation would cause a denial of service. The function reassemble_v2_incoming_fragments() would ignore
    unknown outer payloads but still store these in a fixed size array msg_digest.digest[PAYLIMIT]. An off-by-
    one error in the assertion PASSERT(logger, md->digest_roof < elemsof(md->digest)) causes the daemon to
    abort. No remote code execution is possible. Any configuration that allows IKEv2 connections that do not
    set fragmentation=no are vulnerable. IKEv1 is not affected. (CVE-2026-12413)

  - In FIPS mode, Libreswan's add_decoded_cert() function calls CERT_ExtractPublicKey() and asserts that the
    result is not NULL. However, CERT_ExtractPublicKey() returns NULL when public key extraction fails, for
    example if the RSA exponent is set to 0. A remote attacker can send a malformed X.509 certificate in a
    CERT payload to trigger the assertion, causing the pluto daemon to abort and restart. Continued
    exploitation causes a denial of service. No remote code execution is possible. Both IKEv1 and IKEv2 are
    affected. The vulnerability is only exploitable when both the OS and libreswan are running in FIPS mode
    and at least one CA certificate is loaded. The CERT payload is processed before peer authentication, so no
    credentials are needed to exploit this. Configurations using only PreSharedKey (PSK) authentication with
    no CA certificates loaded in the NSS database are not vulnerable. (CVE-2026-14957)

  - Libreswan, via the function RSA_authenticate_hash_signature_raw_rsa(), did not correctly verify the length
    of the authentication hash when the SIG payload of an IKEv1 packet was encoded using PKCS #1 RSA
    Encryption as per RFC 2313. A remote attacker can use a variation on the Bleichenbacher attack to forge
    the SIG payload when small public exponents are being used (e.g., e=3), which could lead to impersonation.
    Additionally, a remote attacker, by encoding a shorter than expected hash in the SIG payload, could
    trigger an assertion leading to denial-of-service. The daemon aborts and restarts; continued exploitation
    causes sustained denial of service. Remote code execution is not possible. X.509 certificate verifications
    of remote IKE peers are not affected. (CVE-2026-50721)

ID	Name	Product	Family	Type	Severity
373491	Fedora 44 : libreswan (2026-fe33d29b75)	Nessus	Fedora Local Security Checks	Local	medium
372945	Rocky Linux 10.2 [CIQ] Security Update: libreswan / libreswan-debugsource / libreswan-minimal / etc Multiple Vulnerabilities (crlsa-2026_89923)	Nessus	Rocky Linux Local Security Checks	Local	high
372895	Fedora 43 : libreswan (2026-92b72db5d7)	Nessus	Fedora Local Security Checks	Local	medium
372446	RockyLinux 10 : libreswan (RLSA-2026:89923)	Nessus	Rocky Linux Local Security Checks	Local	high
372188	Oracle Linux 10 : libreswan (ELSA-2026-89923)	Nessus	Oracle Linux Local Security Checks	Local	high
372146	RHEL 10 : libreswan (RHSA-2026:89923)	Nessus	Red Hat Local Security Checks	Local	high
369110	Linux Distros Unpatched Vulnerability : CVE-2026-77205	Nessus	Misc.	Local	low
473834	Alpine: multiple libreswan packages: security update to 5.3.3-r0	Tenable Cloud Security	Alpine Linux Local Security Checks	Local	medium
473834	Alpine: multiple libreswan packages: security update to 5.3.3-r0	Tenable Self-Hosted Container Security	Alpine Linux Local Security Checks	Local	medium

Detections

Analytics

CVE-2026-77205

low

Tenable Plugins

medium

high

medium

high

high

high

low

medium

medium