CVE-2026-50721

8.1 HIGH
Published: July 02, 2026 Modified: July 02, 2026
View on NVD

Description

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.

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CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://libreswan.org/security/CVE-2026-50721/
Source: d42dc95b-23f1-4e06-9076-20753a0fb0df
https://libreswan.org/security/CVE-2026-50721/CVE-2026-50721.txt
Source: d42dc95b-23f1-4e06-9076-20753a0fb0df
https://libreswan.org/security/CVE-2026-50722/CVE-2026-50722.txt
Source: d42dc95b-23f1-4e06-9076-20753a0fb0df
https://www.rfc-editor.org/rfc/rfc2313
Source: d42dc95b-23f1-4e06-9076-20753a0fb0df

4 reference(s) from NVD

Quick Stats

CVSS v3 Score
8.1 / 10.0
EPSS (Exploit Probability)
0.4%
29th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)