CVE-2026-50721

HIGHNVD 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 — Patch released this week
8.1EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.9Exploit: None knownExposed: 0

A fix is available — apply it.

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 PROB
0%
EPSS %ILE
31%
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(6)

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

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatlibreswan-0:5.3.2-1.el9fdp2026-07-27redhat
redhatlibreswan-0:5.3.2-1.el10_22026-07-27redhat
redhatlibreswan-0:4.12-2.el8_10.62026-07-27redhat
redhatlibreswan-0:4.15-10.el9_82026-07-27redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 18× in last 7d / 87× 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. 2026-07-28 04:26 UTCVendor advisory
  2. 2026-07-28 04:26 UTCGHSA enrichment
  3. 2026-07-27 15:52 UTCEG score recompute
  4. 2026-07-27 15:52 UTCVendor advisory
  5. 2026-07-27 15:52 UTCGHSA enrichment
  6. 2026-07-27 01:33 UTCEG score recompute
  7. 2026-07-27 01:33 UTCVendor advisory
  8. 2026-07-27 01:33 UTCGHSA enrichment
  9. 2026-07-26 14:54 UTCEPSS rescore
  10. 2026-07-26 13:00 UTCEG score recompute
  11. 2026-07-26 13:00 UTCVendor advisory
  12. 2026-07-26 13:00 UTCGHSA enrichment
  13. 2026-07-25 14:18 UTCEPSS rescore
  14. 2026-07-24 14:18 UTCEPSS rescore
  15. 2026-07-23 14:18 UTCEPSS rescore
  16. 2026-07-23 03:18 UTCEG score recompute
  17. 2026-07-22 14:08 UTCEPSS rescore
  18. 2026-07-21 15:25 UTCEPSS rescore
  19. 2026-07-20 17:08 UTCEPSS rescore
  20. 2026-07-19 14:31 UTCEPSS rescore
  21. 2026-07-19 14:31 UTCEPSS rescore
  22. 2026-07-19 02:29 UTCEPSS rescore
  23. 2026-07-18 10:04 UTCEPSS rescore
  24. 2026-07-17 02:58 UTCVendor advisory
  25. 2026-07-17 02:58 UTCGHSA enrichment
Show 62 more
  1. 2026-07-16 17:03 UTCEPSS rescore
  2. 2026-07-16 14:26 UTCVendor advisory
  3. 2026-07-16 14:26 UTCGHSA enrichment
  4. 2026-07-16 01:51 UTCVendor advisory
  5. 2026-07-16 01:51 UTCGHSA enrichment
  6. 2026-07-15 16:57 UTCEPSS rescore
  7. 2026-07-15 16:57 UTCEPSS rescore
  8. 2026-07-15 13:18 UTCVendor advisory
  9. 2026-07-15 13:18 UTCGHSA enrichment
  10. 2026-07-15 02:00 UTCEPSS rescore
  11. 2026-07-15 02:00 UTCEPSS rescore
  12. 2026-07-15 00:46 UTCVendor advisory
  13. 2026-07-15 00:46 UTCGHSA enrichment
  14. 2026-07-14 12:13 UTCVendor advisory
  15. 2026-07-14 12:13 UTCGHSA enrichment
  16. 2026-07-13 23:41 UTCGHSA enrichment
  17. 2026-07-13 22:31 UTCEPSS rescore
  18. 2026-07-13 11:09 UTCGHSA enrichment
  19. 2026-07-13 06:13 UTCEPSS rescore
  20. 2026-07-13 06:13 UTCEPSS rescore
  21. 2026-07-12 22:37 UTCVendor advisory
  22. 2026-07-12 22:37 UTCGHSA enrichment
  23. 2026-07-12 10:05 UTCVendor advisory
  24. 2026-07-12 10:05 UTCGHSA enrichment
  25. 2026-07-12 05:46 UTCEPSS rescore
  26. 2026-07-11 21:33 UTCVendor advisory
  27. 2026-07-11 21:33 UTCGHSA enrichment
  28. 2026-07-11 09:01 UTCVendor advisory
  29. 2026-07-11 09:01 UTCGHSA enrichment
  30. 2026-07-11 08:27 UTCEPSS rescore
  31. 2026-07-11 08:27 UTCEPSS rescore
  32. 2026-07-10 20:29 UTCVendor advisory
  33. 2026-07-10 20:29 UTCGHSA enrichment
  34. 2026-07-10 07:57 UTCVendor advisory
  35. 2026-07-10 07:57 UTCGHSA enrichment
  36. 2026-07-09 19:25 UTCGHSA enrichment
  37. 2026-07-09 19:10 UTCEPSS rescore
  38. 2026-07-09 19:10 UTCEPSS rescore
  39. 2026-07-09 15:53 UTCNVD updateCVSS v3 → 5.9 · severity → MEDIUM
  40. 2026-07-09 06:52 UTCGHSA enrichment
  41. 2026-07-08 18:19 UTCGHSA enrichment
  42. 2026-07-08 15:16 UTCEPSS rescore
  43. 2026-07-08 15:16 UTCEPSS rescore
  44. 2026-07-08 05:46 UTCGHSA enrichment
  45. 2026-07-07 18:19 UTCNVD updateCVSS v3 → 8.1
  46. 2026-07-07 17:31 UTCMITRE cvelistV5CVSS v3 → 7.5
  47. 2026-07-07 17:11 UTCGHSA enrichment
  48. 2026-07-07 13:46 UTCEPSS rescore
  49. 2026-07-07 13:46 UTCEPSS rescore
  50. 2026-07-07 04:34 UTCGHSA enrichment
  51. 2026-07-06 16:27 UTCEPSS rescore
  52. 2026-07-06 16:01 UTCGHSA enrichment
  53. 2026-07-06 03:28 UTCGHSA enrichment
  54. 2026-07-06 02:23 UTCEPSS rescore
  55. 2026-07-05 14:53 UTCGHSA enrichment
  56. 2026-07-05 02:30 UTCEPSS rescore
  57. 2026-07-05 02:18 UTCGHSA enrichment
  58. 2026-07-04 13:45 UTCGHSA enrichment
  59. 2026-07-04 01:14 UTCGHSA enrichment
  60. 2026-07-03 12:40 UTCGHSA enrichment
  61. 2026-07-03 00:07 UTCEG score recompute
  62. 2026-07-03 00:06 UTCNVD updatefirst tracked

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 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 0% probability of exploitation in the next 30 days, which ranks it in the top 68.7% of all scored CVEs.
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

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