Alibaba Cloud Linux 3 : 0238: libreswan (ALINUX3-SA-2026:0238)

medium Nessus Plugin ID 333575

Synopsis

The remote Alibaba Cloud Linux host is missing a security update.

Description

The remote Alibaba Cloud Linux 3 host has a package installed that is affected by multiple vulnerabilities as referenced in the ALINUX3-SA-2026:0238 advisory.

Package updates are available for Alibaba Cloud Linux 3 that fix the following vulnerabilities:

CVE-2026-12413:
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-2026-14957:
No description is available for this CVE.

CVE-2026-50721:
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-2026-50722:
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.

Tenable has extracted the preceding description block directly from the Alibaba Cloud 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.

Solution

Update the affected libreswan package.

Plugin Details

Severity: Medium

ID: 333575

File Name: alinux3_sa_2026-0238.nasl

Version: 1.1

Type: Local

Family: Alibaba Cloud Linux Local Security Checks

Published: 8/10/2026

Updated: 8/10/2026

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.8

CVSS v2

Risk Factor: Medium

Base Score: 5.4

Temporal Score: 4

Vector: CVSS2#AV:N/AC:H/Au:N/C:N/I:N/A:C

CVSS Score Source: CVE-2026-50722

CVSS v3

Risk Factor: Medium

Base Score: 5.9

Temporal Score: 5.2

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:alibabacloud:alibaba_cloud_linux_3, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:libreswan

Required KB Items: Host/local_checks_enabled, Host/Alibaba/release, Host/Alibaba/rpm-list, Host/cpu

Exploit Ease: No known exploits are available

Patch Publication Date: 8/5/2026

Vulnerability Publication Date: 7/2/2026

Reference Information

CVE: CVE-2026-12413, CVE-2026-14957, CVE-2026-50721, CVE-2026-50722

Detections

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