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 — 4 sources updated 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
33%
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(13)

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

Patch Availability(11)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatrhcos-4.19.9.6.202609021231-02026-09-09redhat
redhatrhcos-4.21.9.6.202609021100-02026-09-08redhat
redhatrhcos-4.20.9.6.202609021029-02026-09-08redhat
redhatlibreswan-0:4.9-5.el9_2.52026-08-31redhat
redhatlibreswan-0:4.12-3.el9_4.22026-08-31redhat
redhatlibreswan-0:4.15-8.el9_6.12026-08-20redhat
redhatlibreswan-0:5.2-1.el10_0.52026-08-17redhat
redhatlibreswan-0:5.3.2-1.el10_22026-07-27redhat
redhatlibreswan-0:4.12-2.el8_10.62026-07-27redhat
redhatlibreswan-0:5.3.2-1.el9fdp2026-07-27redhat
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.

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
libreswan4.10-1 ... 5.2-2.4 (27 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
libreswan4.10-2 ... 5.2-2.5 (18 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
libreswan5.2-2.2, 5.2-2.3, 5.2-2.4, 5.2-2.5——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
libreswan5.2-2.2, 5.2-2.3, 5.2-2.45.2-2.5—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 16× in last 7d / 74× 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.

Showing the most recent 100 of 290 total refreshes for this CVE.

  1. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 06:13 UTCEG score recompute
  3. 2026-09-18 06:13 UTCVendor advisory
  4. 2026-09-18 06:13 UTCGHSA enrichment
  5. 2026-09-16 14:08 UTCEPSS rescore
  6. 2026-09-16 05:15 UTCEPSS rescore
  7. 2026-09-14 00:14 UTCEG score recompute
  8. 2026-09-14 00:14 UTCVendor advisory
  9. 2026-09-14 00:14 UTCGHSA enrichment
  10. 2026-09-13 16:47 UTCEPSS rescore
  11. 2026-09-13 08:58 UTCEG score recompute
  12. 2026-09-13 08:58 UTCVendor advisory
  13. 2026-09-13 08:58 UTCGHSA enrichment
  14. 2026-09-12 14:14 UTCEG score recompute
  15. 2026-09-12 14:14 UTCVendor advisory
  16. 2026-09-12 14:14 UTCGHSA enrichment
  17. 2026-09-11 14:53 UTCEPSS rescore
  18. 2026-09-10 09:35 UTCEPSS rescore
  19. 2026-09-08 22:01 UTCEPSS rescore
  20. 2026-09-07 16:01 UTCEPSS rescore
  21. 2026-09-06 14:19 UTCEG score recompute
  22. 2026-09-06 14:19 UTCVendor advisory
  23. 2026-09-06 14:19 UTCGHSA enrichment
  24. 2026-09-06 13:47 UTCEPSS rescore
  25. 2026-09-05 23:51 UTCEG score recompute
Show 75 more
  1. 2026-09-05 23:51 UTCVendor advisory
  2. 2026-09-05 23:51 UTCGHSA enrichment
  3. 2026-09-04 05:06 UTCEPSS rescore
  4. 2026-09-02 14:12 UTCEPSS rescore
  5. 2026-09-01 13:54 UTCEPSS rescore
  6. 2026-09-01 04:40 UTCEPSS rescore
  7. 2026-08-30 23:54 UTCEG score recompute
  8. 2026-08-30 23:54 UTCVendor advisory
  9. 2026-08-30 23:54 UTCGHSA enrichment
  10. 2026-08-30 19:17 UTCEPSS rescore
  11. 2026-08-30 11:21 UTCEG score recompute
  12. 2026-08-30 11:21 UTCVendor advisory
  13. 2026-08-30 11:21 UTCGHSA enrichment
  14. 2026-08-30 01:22 UTCEPSS rescore
  15. 2026-08-28 21:41 UTCEPSS rescore
  16. 2026-08-27 22:13 UTCEG score recompute
  17. 2026-08-27 22:13 UTCVendor advisory
  18. 2026-08-27 22:13 UTCGHSA enrichment
  19. 2026-08-27 14:25 UTCEPSS rescore
  20. 2026-08-26 14:46 UTCEPSS rescore
  21. 2026-08-25 13:49 UTCEPSS rescore
  22. 2026-08-25 13:39 UTCVendor advisory
  23. 2026-08-25 13:39 UTCGHSA enrichment
  24. 2026-08-24 22:47 UTCEG score recompute
  25. 2026-08-24 22:47 UTCVendor advisory
  26. 2026-08-24 22:47 UTCGHSA enrichment
  27. 2026-08-24 10:15 UTCEG score recompute
  28. 2026-08-24 10:15 UTCVendor advisory
  29. 2026-08-24 10:15 UTCGHSA enrichment
  30. 2026-08-23 20:25 UTCVendor advisory
  31. 2026-08-23 20:25 UTCGHSA enrichment
  32. 2026-08-23 07:53 UTCEG score recompute
  33. 2026-08-23 07:53 UTCVendor advisory
  34. 2026-08-23 07:53 UTCGHSA enrichment
  35. 2026-08-23 00:19 UTCEPSS rescore
  36. 2026-08-22 19:20 UTCVendor advisory
  37. 2026-08-22 19:20 UTCGHSA enrichment
  38. 2026-08-22 06:31 UTCEG score recompute
  39. 2026-08-22 06:31 UTCVendor advisory
  40. 2026-08-22 06:31 UTCGHSA enrichment
  41. 2026-08-21 23:49 UTCEPSS rescore
  42. 2026-08-21 17:58 UTCVendor advisory
  43. 2026-08-21 17:58 UTCGHSA enrichment
  44. 2026-08-21 05:26 UTCEG score recompute
  45. 2026-08-21 05:26 UTCVendor advisory
  46. 2026-08-21 05:26 UTCGHSA enrichment
  47. 2026-08-20 22:55 UTCEPSS rescore
  48. 2026-08-20 16:54 UTCVendor advisory
  49. 2026-08-20 16:54 UTCGHSA enrichment
  50. 2026-08-20 03:59 UTCEG score recompute
  51. 2026-08-20 03:59 UTCVendor advisory
  52. 2026-08-20 03:59 UTCGHSA enrichment
  53. 2026-08-19 17:04 UTCEPSS rescore
  54. 2026-08-19 09:51 UTCVendor advisory
  55. 2026-08-19 09:51 UTCGHSA enrichment
  56. 2026-08-18 20:53 UTCEG score recompute
  57. 2026-08-18 20:53 UTCVendor advisory
  58. 2026-08-18 20:53 UTCGHSA enrichment
  59. 2026-08-18 13:48 UTCEPSS rescore
  60. 2026-08-18 06:19 UTCVendor advisory
  61. 2026-08-18 06:19 UTCGHSA enrichment
  62. 2026-08-17 16:54 UTCEG score recompute
  63. 2026-08-17 16:54 UTCVendor advisory
  64. 2026-08-17 16:54 UTCGHSA enrichment
  65. 2026-08-17 13:47 UTCEPSS rescore
  66. 2026-08-17 04:22 UTCVendor advisory
  67. 2026-08-17 04:22 UTCGHSA enrichment
  68. 2026-08-16 15:49 UTCEG score recompute
  69. 2026-08-16 15:49 UTCVendor advisory
  70. 2026-08-16 15:49 UTCGHSA enrichment
  71. 2026-08-16 14:56 UTCEPSS rescore
  72. 2026-08-16 03:17 UTCEG score recompute
  73. 2026-08-16 03:17 UTCVendor advisory
  74. 2026-08-16 03:17 UTCGHSA enrichment
  75. 2026-08-16 02:14 UTCEPSS rescore

Related CVEs(same vendor + 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 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 67.4% 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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