Improper Verification of Cryptographic Signature Affecting libreswan-debugsource package, versions <0:4.12-3.amzn2023.0.3


Severity

Recommended
0.0
high
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.39% (31st percentile)

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  • Snyk IDSNYK-AMZN2023-LIBRESWANDEBUGSOURCE-18530959
  • published5 Aug 2026
  • disclosed2 Jul 2026

Introduced: 2 Jul 2026

CVE-2026-50721  (opens in a new tab)
CWE-347  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 libreswan-debugsource to version 0:4.12-3.amzn2023.0.3 or higher.
This issue was patched in ALAS2023-2026-2039.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libreswan-debugsource package and not the libreswan-debugsource package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1