CVE-2026-50721
IKEv1 Denial of Service via RSA-SHA1 (PKCS#1 Version 1.5 Encrypted) authentication payload
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.
INFO
Published Date :
July 2, 2026, 9:44 p.m.
Last Modified :
July 2, 2026, 9:44 p.m.
Remotely Exploit :
Yes !
Source :
libreswan
Affected Products
The following products are affected by CVE-2026-50721
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | d42dc95b-23f1-4e06-9076-20753a0fb0df | ||||
| CVSS 3.1 | HIGH | d42dc95b-23f1-4e06-9076-20753a0fb0df |
Solution
- Update Libreswan to the latest version.
- Verify signature verification logic.
- Monitor for impersonation attempts.
- Monitor for denial-of-service attacks.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-50721 vulnerability anywhere in the article.