CVE-2026-50721

HIGHPre-NVD 8.18.1—
EchelonGraph scoreHIGH confidence

Score 8.1 from GitHub Security Advisory (severity: HIGH) published 2026-07-03. a secondary CVSS source baseline 8.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 4 sources updated this week
8.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 8.1Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
8.1
EG Score
8.1(high)
EPSS
28.7%
KEV
Not listed

Published

July 2, 2026

Last Modified

July 6, 2026

Advisory Details (4)

Auto-updated Jul 3, 2026
No patch confirmed yet.
generic

RFC 2313: PKCS #1: RSA Encryption Version 1.5 | RFC Editor

https://www.rfc-editor.org/rfc/rfc2313
generic
https://libreswan.org/security/CVE-2026-50722/CVE-2026-50722.txt
generic
https://libreswan.org/security/CVE-2026-50721/CVE-2026-50721.txt
generic

Index of /security/CVE-2026-50721/

https://libreswan.org/security/CVE-2026-50721/

Vendor Advisories for CVE-2026-50721(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 19× in last 7d / 19× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-06 16:27 UTCEPSS rescore
  2. 2026-07-06 16:01 UTCEG score recompute
  3. 2026-07-06 16:01 UTCGHSA enrichment
  4. 2026-07-06 03:28 UTCEG score recompute
  5. 2026-07-06 03:28 UTCGHSA enrichment
  6. 2026-07-06 02:23 UTCEPSS rescore
  7. 2026-07-05 14:53 UTCEG score recompute
  8. 2026-07-05 14:53 UTCGHSA enrichment
  9. 2026-07-05 02:30 UTCEPSS rescore
  10. 2026-07-05 02:18 UTCEG score recompute
  11. 2026-07-05 02:18 UTCGHSA enrichment
  12. 2026-07-04 13:46 UTCEG score recompute
  13. 2026-07-04 13:45 UTCGHSA enrichment
  14. 2026-07-04 01:14 UTCEG score recompute
  15. 2026-07-04 01:14 UTCGHSA enrichment
  16. 2026-07-03 12:41 UTCEG score recompute
  17. 2026-07-03 12:40 UTCGHSA enrichment
  18. 2026-07-03 00:07 UTCEG score recompute
  19. 2026-07-03 00:06 UTCNVD updatefirst tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-50721?
CVE-2026-50721 is a high vulnerability published on July 2, 2026. Libreswan, via the function RSAauthenticatehashsignatureraw_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…
When was CVE-2026-50721 disclosed?
CVE-2026-50721 was first published in the National Vulnerability Database on July 2, 2026, with the most recent update on July 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-50721 actively exploited?
CVE-2026-50721 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 28.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-50721?
CVE-2026-50721 has a CVSS v3 base score of 8.1 (NVD).
How do I remediate CVE-2026-50721?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-50721, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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