Libreswan's IKEv2 state machine has a null pointer dereference bug in the EAP handling code for authentication. As a result of inconsistency within the IKEv2 state machine code, this bug can be triggered by any IKEv2 connection, even if EAP is not configured at all. The error is caused by a fall-through where it incorrectly dereferences ike->sa.st_eap which is NULL. A malicious IKE_AUTH packet can trigger this bug, meaning the peer does not need to be authenticated. The bug results in a crash and restart of the pluto daemon. No remote code execution is possible. Continued exploitation can cause a denial of service.

The remote MiracleLinux 8 host has a package installed that is affected by multiple vulnerabilities as referenced in the AXSA:2026-2190:04 advisory.

    * libreswan: IKEv2 Use-After-Free bug when using IKE-over-TCP (CVE-2026-94453)
      * libreswan: IKEv2 pre-authentication Null Pointer deref in EAP code (CVE-2026-77206)
      * libreswan: Null Pointer Dereference in PKCS#7 bundle with no CERTS (CVE-2026-77207)

Tenable has extracted the preceding description block directly from the MiracleLinux 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 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the CIQ crlsa-2026_89748 advisory.

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

    * libreswan: IKEv2 pre-authentication Null Pointer deref in EAP code (CVE-2026-77206)

    * 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 MiracleLinux 9 host has a package installed that is affected by multiple vulnerabilities as referenced in the AXSA:2026-2176:03 advisory.

    * libreswan: IKEv2 Use-After-Free bug when using IKE-over-TCP (CVE-2026-94453)
      * libreswan: IKEv2 pre-authentication Null Pointer deref in EAP code (CVE-2026-77206)
      * libreswan: Null Pointer Dereference in PKCS#7 bundle with no CERTS (CVE-2026-77207)

Tenable has extracted the preceding description block directly from the MiracleLinux 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 Oracle Linux 8 host has a package installed that is affected by multiple vulnerabilities as referenced in the ELSA-2026-90492 advisory.

    - Backport fixes for CVE-2026-94453, CVE-2026-77206 and CVE-2026-77207 (RHEL-281879, RHEL-282682,     RHEL-282477)
    - Backport fix for CVE-2026-14957 (RHEL-212498)
    - Backport fixes for CVE-2026-12413, CVE-2026-50721 and CVE-2026-50722 (RHEL-190146, RHEL-190140,     RHEL-190132)
    - Fix CVE-2024-3652 (RHEL-32482)

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 RockyLinux 9 host has packages installed that are affected by multiple vulnerabilities as referenced in the RLSA-2026:89748 advisory.

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

    * libreswan: IKEv2 pre-authentication Null Pointer deref in EAP code (CVE-2026-77206)

    * 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 AlmaLinux 9 host has a package installed that is affected by multiple vulnerabilities as referenced in the ALSA-2026:89748 advisory.

    * libreswan: IKEv2 Use-After-Free bug when using IKE-over-TCP (CVE-2026-94453)
      * libreswan: IKEv2 pre-authentication Null Pointer deref in EAP code (CVE-2026-77206)
      * libreswan: Null Pointer Dereference in PKCS#7 bundle with no CERTS (CVE-2026-77207)

Tenable has extracted the preceding description block directly from the AlmaLinux 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 AlmaLinux 8 host has a package installed that is affected by multiple vulnerabilities as referenced in the ALSA-2026:90492 advisory.

    * libreswan: IKEv2 Use-After-Free bug when using IKE-over-TCP (CVE-2026-94453)
      * libreswan: IKEv2 pre-authentication Null Pointer deref in EAP code (CVE-2026-77206)
      * libreswan: Null Pointer Dereference in PKCS#7 bundle with no CERTS (CVE-2026-77207)

Tenable has extracted the preceding description block directly from the AlmaLinux 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 9 host has a package installed that is affected by multiple vulnerabilities as referenced in the ELSA-2026-89748 advisory.

    [4.15-11.0.1]
    - Add libreswan-oracle.patch to detect Oracle Linux distro

    [4.15-11]
    - Backport fixes for CVE-2026-94453, CVE-2026-77206, and CVE-2026-77207 (RHEL-281889, RHEL-281998,     RHEL-281985)

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 9 host has a package installed that is affected by multiple vulnerabilities as referenced in the RHSA-2026:89748 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: IKEv2 pre-authentication Null Pointer deref in EAP code (CVE-2026-77206)

    * 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's IKEv2 state machine has a null pointer dereference bug in the EAP handling code for     authentication. As a result of inconsistency within the IKEv2 state machine code, this bug can be     triggered by any IKEv2 connection, even if EAP is not configured at all. The error is caused by a fall-     through where it incorrectly dereferences ike->sa.st_eap which is NULL. A malicious IKE_AUTH packet can     trigger this bug, meaning the peer does not need to be authenticated. The bug results in a crash and     restart of the pluto daemon. No remote code execution is possible. Continued exploitation can cause a     denial of service. (CVE-2026-77206)

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
373040	MiracleLinux 8 : libreswan-4.12-2.el8_10.7 (AXSA:2026-2190:04)	Nessus	Miracle Linux Local Security Checks	Local	high
372954	Rocky Linux 9 [CIQ] Security Update: libreswan / libreswan-debuginfo / libreswan-debugsource Multiple Vulnerabilities (crlsa-2026_89748)	Nessus	Rocky Linux Local Security Checks	Local	high
372916	MiracleLinux 9 : libreswan-4.15-11.el9_8 (AXSA:2026-2176:03)	Nessus	Miracle Linux Local Security Checks	Local	high
372895	Fedora 43 : libreswan (2026-92b72db5d7)	Nessus	Fedora Local Security Checks	Local	medium
372477	Oracle Linux 8 : libreswan (ELSA-2026-90492)	Nessus	Oracle Linux Local Security Checks	Local	high
372425	RockyLinux 9 : libreswan (RLSA-2026:89748)	Nessus	Rocky Linux Local Security Checks	Local	high
372208	AlmaLinux 9 : libreswan (ALSA-2026:89748)	Nessus	Alma Linux Local Security Checks	Local	high
372205	AlmaLinux 8 : libreswan (ALSA-2026:90492)	Nessus	Alma Linux Local Security Checks	Local	high
372062	Oracle Linux 9 : libreswan (ELSA-2026-89748)	Nessus	Oracle Linux Local Security Checks	Local	high
371999	RHEL 9 : libreswan (RHSA-2026:89748)	Nessus	Red Hat Local Security Checks	Local	high
369151	Linux Distros Unpatched Vulnerability : CVE-2026-77206	Nessus	Misc.	Local	high
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-2026-77206

high

Tenable Plugins

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