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: 0.5%, top 57% of all CVEs by exploit prediction. 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 — Patch released this week
6.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 6.3Exploit: None knownExposed: 0

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
6.3(medium)
EG Risk
44(Track)
EG Risk 44/100SSVC: 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
Severity63% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
43%
KEV
Not listed

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
github Patch Available

HTTP Header smuggling · Advisory · libevent/libevent · GitHub

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

Vendor Advisories for CVE-2026-63379(1)

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

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
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 rangeFixed inDependents
libevent2.1.12-stable-10 ... 2.1.13-stable-1 (7 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
libevent2.1.12-stable-10, 2.1.13-stable-1——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
libevent2.1.12-stable-102.1.13-stable-1—

Weakness Classification(1)

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

Additional Vendor Advisories

(2)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 16× in last 7d / 65× 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. 2026-09-19 07:06 UTCEG score recompute
  2. 2026-09-19 07:06 UTCVendor advisory
  3. 2026-09-18 19:28 UTCEPSS rescore
  4. 2026-09-18 06:17 UTCEG score recompute
  5. 2026-09-18 06:17 UTCVendor advisory
  6. 2026-09-17 05:29 UTCEG score recompute
  7. 2026-09-17 05:29 UTCVendor advisory
  8. 2026-09-16 14:08 UTCEPSS rescore
  9. 2026-09-16 05:15 UTCEPSS rescore
  10. 2026-09-16 04:40 UTCVendor advisory
  11. 2026-09-15 03:35 UTCEG score recompute
  12. 2026-09-15 03:35 UTCVendor advisory
  13. 2026-09-14 02:45 UTCEG score recompute
  14. 2026-09-14 02:45 UTCVendor advisory
  15. 2026-09-13 01:56 UTCEG score recompute
  16. 2026-09-13 01:56 UTCVendor advisory
  17. 2026-09-12 01:07 UTCEG score recompute
  18. 2026-09-12 01:07 UTCVendor advisory
  19. 2026-09-11 14:53 UTCEPSS rescore
  20. 2026-09-11 09:37 UTCEPSS rescore
  21. 2026-09-11 00:18 UTCEG score recompute
  22. 2026-09-11 00:18 UTCVendor advisory
  23. 2026-09-09 22:34 UTCVendor advisory
  24. 2026-09-09 04:46 UTCEG score recompute
  25. 2026-09-09 04:46 UTCVendor advisory
Show 43 more
  1. 2026-09-08 22:01 UTCEPSS rescore
  2. 2026-09-08 03:48 UTCEG score recompute
  3. 2026-09-08 03:48 UTCVendor advisory
  4. 2026-09-07 16:01 UTCEPSS rescore
  5. 2026-09-07 02:59 UTCEG score recompute
  6. 2026-09-07 02:59 UTCVendor advisory
  7. 2026-09-06 13:47 UTCEPSS rescore
  8. 2026-09-06 02:10 UTCEG score recompute
  9. 2026-09-06 02:10 UTCVendor advisory
  10. 2026-09-05 15:31 UTCEPSS rescore
  11. 2026-09-05 01:22 UTCEG score recompute
  12. 2026-09-05 01:22 UTCVendor advisory
  13. 2026-09-04 05:07 UTCEPSS rescore
  14. 2026-09-04 00:27 UTCVendor advisory
  15. 2026-09-02 23:37 UTCEG score recompute
  16. 2026-09-02 23:37 UTCVendor advisory
  17. 2026-09-02 14:12 UTCEPSS rescore
  18. 2026-09-01 22:47 UTCEG score recompute
  19. 2026-09-01 22:47 UTCVendor advisory
  20. 2026-09-01 13:54 UTCEPSS rescore
  21. 2026-09-01 04:40 UTCEPSS rescore
  22. 2026-08-31 21:58 UTCVendor advisory
  23. 2026-08-30 21:10 UTCEG score recompute
  24. 2026-08-30 21:10 UTCVendor advisory
  25. 2026-08-30 19:17 UTCEPSS rescore
  26. 2026-08-30 01:22 UTCEPSS rescore
  27. 2026-08-29 20:21 UTCEG score recompute
  28. 2026-08-28 21:42 UTCEPSS rescore
  29. 2026-08-27 18:42 UTCEG score recompute
  30. 2026-08-27 14:25 UTCEPSS rescore
  31. 2026-08-26 17:53 UTCEG score recompute
  32. 2026-08-26 14:46 UTCEPSS rescore
  33. 2026-08-25 16:26 UTCEG score recompute
  34. 2026-08-25 15:31 UTCEG score recompute
  35. 2026-08-25 13:49 UTCEPSS rescore
  36. 2026-08-24 21:31 UTCEG score recompute
  37. 2026-08-23 20:43 UTCEG score recompute
  38. 2026-08-23 00:19 UTCEPSS rescore
  39. 2026-08-22 19:55 UTCEG score recompute
  40. 2026-08-21 23:49 UTCEPSS rescore
  41. 2026-08-20 18:17 UTCEG score recompute
  42. 2026-08-20 18:07 UTCEG score recompute
  43. 2026-08-20 18:06 UTCMITRE cvelistV5first tracked

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 in the National Vulnerability Database 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 1% probability of exploitation in the next 30 days, which ranks it in the top 56.9% of all scored CVEs.
What is the CVSS score of CVE-2026-63379?
CVE-2026-63379 has a CVSS v3 base score of 6.3 (NVD).
How do I remediate CVE-2026-63379?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63379, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-63379

Explore →

Is Your Infrastructure Affected by CVE-2026-63379?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs