CVE-2026-50721
CVE-2026-50721: 1 tracked advisory record across Red Hat. Compare source-reported impact, fixes and remediation.
Compare the source-linked records below. Ratings and product/version details belong to each advisory; they are not a single CVE-wide score or proof that every listed product is affected. How VulniPulse collects and checks evidence.
Vendor advisory comparison
Red Hat
1 advisory- Advisory severityHigh7.5
High [CVE-2026-50721] IKEv1 Denial of Service via RSA-SHA1 (PKCS#1 Version 1.5 Encrypted) authentication payload
CVE-2026-50721Source published Source updated
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. A remote, unauthenticated…
- Affected products in this advisory
- Fast Datapath for Red Hat Enterprise Linux 9
- Red Hat Enterprise Linux 10.0 Extended Update Support
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9.6 Extended Update Support
4 more entries in the full advisory.
- Source-reported affected versions
- Affected-version details not available in this record.
- Source-reported fixed versions
- libreswan-0:5.3.2-1.el9fdp
- libreswan-0:5.3.2-1.el10_2
- libreswan-0:5.2-1.el10_0.5
- libreswan-0:4.12-2.el8_10.6
8 more entries in the full advisory.
- Mitigation guidance
- To mitigate this vulnerability, consider the following strategic workarounds if upgrading Libreswan immediately is not viable: - Migrate to IKEv2: Disable IKEv1 entirely and migrate all connections to IKEv2. The vulnerable code path is tied specifically to IKEv1’s rigid handling of PKCS#1 v1.5 RSA-SHA1. - Switch to Pre-Shared Keys (PSK): Additionally, if the configuration is for static tunnels, and not for a group of Remote Access VPN Clients, the authentication can be changed to use PSK via "authby=secret" after coordination with the remote peer.
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