CVE-2026-50721

8.1 HIGH 0.4% exploit odds Fix listed Crypto

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of data exposure, data tampering, service disruption.
Exploit odds: 0.4% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-07-02 22:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-25 21:10 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.4% in the next 30 days (EPSS).
Severity: 8.1 HIGH (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-07-02 22:16 UTC
Last modified: 2026-10-25 21:10 UTC
Exploit probability: 0.4% · EPSS, next 30 days
Weakness: CWE-347
Record status: Analyzed

Affected

Libreswan < 5.3.1

Attack profile CVSS 3.1 · 8.1

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Raw vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Is it in your code?

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Fix and advisories

References

NVD record · CVE.org record