CVE-2026-63379

MEDIUMPre-NVD 6.36.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.7% (51st percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
6.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.7%CVSS: 6.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent processes chunked HTTP trailers in http.c through evhttp_read_trailer and merges them into request headers. The fix introduces evhttp_parse_headers_impl_ and a temporary trailer header list. An unauthenticated remote attacker can place security-sensitive fields in trailers so that an upstream proxy and the libevent application interpret different effective headers, enabling header smuggling, authorization bypass, proxy-header spoofing, or cache poisoning. The fix parses trailers into a temporary header list and discards them instead of merging them into req->input_headers. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

CVSS v3
6.3
EG Score
6.3MEDIUMmedium confidence
EG Risk
44
EG Risk 44/100CISA SSVC

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
Severity63% × 45%
Exploitation1% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.7%
EPSS %ILE
52nd
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

August 20, 2026

Last Modified

September 9, 2026

Advisory Details (5)

Auto-updated Aug 20, 2026
Patch available. Sources: github, github_commit, github_release.
github_release Patch Available

Libevent 2.2.2-alpha

Patch available: libevent/libevent release-2.2.2-alpha

https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha
github_release Patch Available

Libevent 2.1.13-stable

Patch available: libevent/libevent release-2.1.13-stable

https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable
github_commit Patch Available

commit b847071141b3 (libevent/libevent)

Patch available: libevent/libevent release-2.2.2-alpha (contains commit b847071141b3)

https://github.com/libevent/libevent/commit/b847071141b3827900d536594ec9045eb0a4c485
github_commit Patch Available

commit 87e8e44fa774 (libevent/libevent)

Patch available: libevent/libevent release-2.1.13-stable (contains commit 87e8e44fa774)

https://github.com/libevent/libevent/commit/87e8e44fa774e9677b089b1a5114ee68aefa1636
githubMentions a patch (unverified)

HTTP Header smuggling · Advisory · libevent/libevent · GitHub

https://github.com/libevent/libevent/security/advisories/GHSA-2gmv-p5m7-98p6

Vendor Advisories for CVE-2026-63379(11)

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

Patch Availability(10)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatcert-manager/cert-manager-operator-rhel9:17905898552026-09-28redhat
redhatcert-manager/jetstack-cert-manager-rhel9:17905899122026-09-28redhat
redhatcert-manager/cert-manager-istio-csr-rhel9:17905899142026-09-28redhat
redhatcert-manager/cert-manager-operator-rhel9:17902724262026-09-28redhat
redhatcert-manager/cert-manager-istio-csr-rhel9:17902237192026-09-28redhat
redhatcert-manager/jetstack-cert-manager-rhel9:17902232792026-09-28redhat
redhatrhui5/rhua-rhel9:17902420042026-09-24redhat
redhatlibevent-0:2.1.13-1.el10_22026-09-16redhat
redhatlibevent-0:2.1.13-1.el9_82026-09-16redhat
redhatlibevent-main-2.1.12-19.1.hum12026-08-29redhat

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

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
libevent2.1.12-stable-8
  • every version up to 2.1.12-stable-8+deb12u1: fixed in 2.1.12-stable-8+deb12u1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
libevent2.1.12-stable-10
  • every version up to 2.1.13-stable-1~deb13u1: fixed in 2.1.13-stable-1~deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
libevent2.1.12-stable-10, 2.1.13-stable-1~deb13u1
  • every version up to 2.1.13-stable-1: fixed in 2.1.13-stable-1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 20× 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 120 total refreshes for this CVE.

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

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-63379?
CVE-2026-63379 is a medium vulnerability published on August 20, 2026. Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent processes chunked HTTP trailers in http.c through evhttpreadtrailer and merges them into request headers. The fix introduces evhttpparseheadersimpl and a temporary trailer header list. An unauthenticated remote…
When was CVE-2026-63379 disclosed?
CVE-2026-63379 was first published on August 20, 2026, with the most recent update on September 9, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63379 actively exploited?
CVE-2026-63379 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (52nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-63379?
CVE-2026-63379 has a CVSS base score of 6.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-63379?
A fix for CVE-2026-63379 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-63379 are linked in the Vendor Advisories panel on this page.

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