CVE-2026-50721

MEDIUMNVD 5.98.1▲
EchelonGraph scoreMEDIUM confidence

Score 8.1 from GitHub Security Advisory (severity: HIGH) published 2026-07-03. NVD baseline CVSS 5.9; sources differ by 2.2.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
5.9
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.9Exploit: 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
5.9
EG Score
8.1(medium)
EG Risk
52(Track)
EG Risk 52/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity81% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
31.7%
KEV
Not listed

Published

July 2, 2026

Last Modified

July 9, 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(2)

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 11× in last 7d / 73× 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. 2026-07-23 14:18 UTCEPSS rescore
  2. 2026-07-23 03:18 UTCEG score recompute
  3. 2026-07-22 14:08 UTCEPSS rescore
  4. 2026-07-21 15:25 UTCEPSS rescore
  5. 2026-07-20 17:08 UTCEPSS rescore
  6. 2026-07-19 14:31 UTCEPSS rescore
  7. 2026-07-19 14:31 UTCEPSS rescore
  8. 2026-07-19 02:29 UTCEPSS rescore
  9. 2026-07-18 10:04 UTCEPSS rescore
  10. 2026-07-17 02:58 UTCVendor advisory
  11. 2026-07-17 02:58 UTCGHSA enrichment
  12. 2026-07-16 17:03 UTCEPSS rescore
  13. 2026-07-16 14:26 UTCVendor advisory
  14. 2026-07-16 14:26 UTCGHSA enrichment
  15. 2026-07-16 01:51 UTCVendor advisory
  16. 2026-07-16 01:51 UTCGHSA enrichment
  17. 2026-07-15 16:57 UTCEPSS rescore
  18. 2026-07-15 16:57 UTCEPSS rescore
  19. 2026-07-15 13:18 UTCVendor advisory
  20. 2026-07-15 13:18 UTCGHSA enrichment
  21. 2026-07-15 02:00 UTCEPSS rescore
  22. 2026-07-15 02:00 UTCEPSS rescore
  23. 2026-07-15 00:46 UTCVendor advisory
  24. 2026-07-15 00:46 UTCGHSA enrichment
  25. 2026-07-14 12:13 UTCVendor advisory
Show 48 more
  1. 2026-07-14 12:13 UTCGHSA enrichment
  2. 2026-07-13 23:41 UTCGHSA enrichment
  3. 2026-07-13 22:31 UTCEPSS rescore
  4. 2026-07-13 11:09 UTCGHSA enrichment
  5. 2026-07-13 06:13 UTCEPSS rescore
  6. 2026-07-13 06:13 UTCEPSS rescore
  7. 2026-07-12 22:37 UTCVendor advisory
  8. 2026-07-12 22:37 UTCGHSA enrichment
  9. 2026-07-12 10:05 UTCVendor advisory
  10. 2026-07-12 10:05 UTCGHSA enrichment
  11. 2026-07-12 05:46 UTCEPSS rescore
  12. 2026-07-11 21:33 UTCVendor advisory
  13. 2026-07-11 21:33 UTCGHSA enrichment
  14. 2026-07-11 09:01 UTCVendor advisory
  15. 2026-07-11 09:01 UTCGHSA enrichment
  16. 2026-07-11 08:27 UTCEPSS rescore
  17. 2026-07-11 08:27 UTCEPSS rescore
  18. 2026-07-10 20:29 UTCVendor advisory
  19. 2026-07-10 20:29 UTCGHSA enrichment
  20. 2026-07-10 07:57 UTCVendor advisory
  21. 2026-07-10 07:57 UTCGHSA enrichment
  22. 2026-07-09 19:25 UTCGHSA enrichment
  23. 2026-07-09 19:10 UTCEPSS rescore
  24. 2026-07-09 19:10 UTCEPSS rescore
  25. 2026-07-09 15:53 UTCNVD updateCVSS v3 → 5.9 · severity → MEDIUM
  26. 2026-07-09 06:52 UTCGHSA enrichment
  27. 2026-07-08 18:19 UTCGHSA enrichment
  28. 2026-07-08 15:16 UTCEPSS rescore
  29. 2026-07-08 15:16 UTCEPSS rescore
  30. 2026-07-08 05:46 UTCGHSA enrichment
  31. 2026-07-07 18:19 UTCNVD updateCVSS v3 → 8.1
  32. 2026-07-07 17:31 UTCMITRE cvelistV5CVSS v3 → 7.5
  33. 2026-07-07 17:11 UTCGHSA enrichment
  34. 2026-07-07 13:46 UTCEPSS rescore
  35. 2026-07-07 13:46 UTCEPSS rescore
  36. 2026-07-07 04:34 UTCGHSA enrichment
  37. 2026-07-06 16:27 UTCEPSS rescore
  38. 2026-07-06 16:01 UTCGHSA enrichment
  39. 2026-07-06 03:28 UTCGHSA enrichment
  40. 2026-07-06 02:23 UTCEPSS rescore
  41. 2026-07-05 14:53 UTCGHSA enrichment
  42. 2026-07-05 02:30 UTCEPSS rescore
  43. 2026-07-05 02:18 UTCGHSA enrichment
  44. 2026-07-04 13:45 UTCGHSA enrichment
  45. 2026-07-04 01:14 UTCGHSA enrichment
  46. 2026-07-03 12:40 UTCGHSA enrichment
  47. 2026-07-03 00:07 UTCEG score recompute
  48. 2026-07-03 00:06 UTCNVD updatefirst tracked

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-50721?
CVE-2026-50721 is a medium 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 9, 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 31.7% 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 5.9 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 8.1.
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

Explore the affected products and dependency analysis for CVE-2026-50721

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