CVE-2026-50722
Last modified
CVE-2026-50722 is a medium-severity vulnerability rated 5.9/10 on the CVSS scale. 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. EPSS estimates a 0.33% chance of exploitation in the next 30 days.
Description
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.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Libreswan | Libreswan | < 5.3.1 |
References
- https://libreswan.org/security/CVE-2026-50721/CVE-2026-50721.txtVendor Advisory, Mailing List
- https://libreswan.org/security/CVE-2026-50722/Vendor Advisory
- https://www.rfc-editor.org/rfc/rfc8017Technical Description
Timeline
- Published
- Last Modified
- Status
- Analyzed
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