CVE-2026-63385

CRITICALPre-NVD 9.29.2—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.2 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (44th 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 — Patch released this week
9.2EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 9.2Exploit: 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 has two HTTP parsing weaknesses in http.c. evhttp_decode_uri_internal decodes percent-encoded %00 bytes into literal NUL characters, which can cause downstream C string operations to truncate a path and bypass validation performed on a different representation. evhttp_header_is_valid_value also accepts obsolete line folding in header values containing carriage return or line feed characters, allowing a proxy and libevent to interpret headers differently and enabling header injection or access control bypass. The CRLF header acceptance is fixed in versions 2.1.13 and 2.2.2-alpha, but the reviewed patches do not clearly remediate the URI NUL-truncation condition.

CVSS v3
9.2
EG Score
9.2CRITICALmedium confidence
EG Risk
42
EG Risk 42/100CISA 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
Severity92% × 45%
Exploitation1% × 40%
Automatability0% × 15%
CISA SSVC: Track at every mission impact level.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.5%
EPSS %ILE
44th
KEV
Not listed

CISA SSVCTrack at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (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 Sep 15, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github.
githubMentions a patch (unverified)🟡 PoC Available

HTTP header handling bugs create risk of access control bypass. · Advisory · libevent/libevent · GitHub

https://github.com/libevent/libevent/security/advisories/GHSA-jcwh-pvf2-73p2
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 9170dd35e647 (libevent/libevent)

Patch available: libevent/libevent release-2.1.13-stable (contains commit 9170dd35e647)

https://github.com/libevent/libevent/commit/9170dd35e64714613e8d13b290587cfc28e258e2
github_commit Patch Available

commit 758be0c0f69c (libevent/libevent)

Patch available: libevent/libevent release-2.2.2-alpha (contains commit 758be0c0f69c)

https://github.com/libevent/libevent/commit/758be0c0f69c1934ef9a84ab39e9f9e5fde2e6d0

Vendor Advisories for CVE-2026-63385(14)

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

Patch Availability(14)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibevent-pthreads-2.1-6 (2.1.8-stable-4ubuntu0.1~esm1) @ bionic2026-10-09ubuntu
redhatopenshift/ose-rhel-coreos-9:4.22.9.8.202609291947-02026-10-06redhat
redhatcert-manager/jetstack-cert-manager-rhel9:17902232792026-09-28redhat
redhatcert-manager/jetstack-cert-manager-rhel9:17905899122026-09-28redhat
redhatcert-manager/cert-manager-operator-rhel9:17902724262026-09-28redhat
redhatcert-manager/cert-manager-operator-rhel9:17905898552026-09-28redhat
redhatcert-manager/cert-manager-istio-csr-rhel9:17902237192026-09-28redhat
redhatcert-manager/cert-manager-istio-csr-rhel9:17905899142026-09-28redhat
redhatrhui5/rhua-rhel9:17902420042026-09-24redhat
redhatlibevent-main-2.1.13-1.hum12026-09-22redhat
redhatlibevent-0:2.1.13-1.el10_22026-09-16redhat
redhatlibevent-0:2.1.8-11.el8_102026-09-16redhat
redhatlibevent-0:2.1.13-1.el9_82026-09-16redhat
redhatlibevent-main-2.1.13-0.1.hum12026-09-03redhat

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.

Additional Vendor Advisories

(1)

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 37× in last 7d / 191× 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 267 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 09:12 UTCVendor advisory
  7. 2026-10-08 05:19 UTCEG score recompute
  8. 2026-10-08 05:19 UTCVendor advisory
  9. 2026-10-07 23:48 UTCEPSS rescore
  10. 2026-10-07 10:06 UTCVendor advisory
  11. 2026-10-07 05:16 UTCVendor advisory
  12. 2026-10-07 01:16 UTCVendor advisory
  13. 2026-10-06 21:19 UTCVendor advisory
  14. 2026-10-06 16:53 UTCEG score recompute
  15. 2026-10-06 16:53 UTCVendor advisory
  16. 2026-10-06 15:18 UTCEPSS rescore
  17. 2026-10-06 12:20 UTCVendor advisory
  18. 2026-10-06 07:52 UTCVendor advisory
  19. 2026-10-06 03:24 UTCVendor advisory
  20. 2026-10-06 03:24 UTCVendor advisory
  21. 2026-10-06 03:24 UTCVendor advisory
  22. 2026-10-06 03:24 UTCVendor advisory
  23. 2026-10-06 03:24 UTCVendor advisory
  24. 2026-10-05 17:44 UTCEG score recompute
  25. 2026-10-05 17:44 UTCVendor advisory
Show 75 more
  1. 2026-10-05 17:43 UTCEPSS rescore
  2. 2026-10-05 13:52 UTCVendor advisory
  3. 2026-10-05 09:29 UTCVendor advisory
  4. 2026-10-05 05:28 UTCVendor advisory
  5. 2026-10-05 01:35 UTCEG score recompute
  6. 2026-10-05 01:35 UTCVendor advisory
  7. 2026-10-04 23:22 UTCEPSS rescore
  8. 2026-10-04 20:52 UTCVendor advisory
  9. 2026-10-04 14:41 UTCVendor advisory
  10. 2026-10-04 10:24 UTCVendor advisory
  11. 2026-10-04 06:31 UTCVendor advisory
  12. 2026-10-04 02:39 UTCVendor advisory
  13. 2026-10-03 20:48 UTCVendor advisory
  14. 2026-10-03 16:47 UTCEG score recompute
  15. 2026-10-03 16:47 UTCVendor advisory
  16. 2026-10-03 14:26 UTCEPSS rescore
  17. 2026-10-03 04:36 UTCVendor advisory
  18. 2026-10-03 00:40 UTCVendor advisory
  19. 2026-10-02 18:55 UTCEG score recompute
  20. 2026-10-02 18:55 UTCVendor advisory
  21. 2026-10-02 17:56 UTCEPSS rescore
  22. 2026-10-02 14:58 UTCVendor advisory
  23. 2026-10-02 11:05 UTCVendor advisory
  24. 2026-10-02 06:49 UTCVendor advisory
  25. 2026-10-02 01:21 UTCVendor advisory
  26. 2026-10-01 21:29 UTCEG score recompute
  27. 2026-10-01 21:29 UTCVendor advisory
  28. 2026-10-01 19:50 UTCEPSS rescore
  29. 2026-10-01 13:30 UTCVendor advisory
  30. 2026-10-01 09:38 UTCVendor advisory
  31. 2026-10-01 05:41 UTCVendor advisory
  32. 2026-10-01 01:13 UTCVendor advisory
  33. 2026-09-30 20:31 UTCEG score recompute
  34. 2026-09-30 20:31 UTCVendor advisory
  35. 2026-09-30 15:03 UTCEPSS rescore
  36. 2026-09-30 12:13 UTCVendor advisory
  37. 2026-09-30 08:13 UTCEG score recompute
  38. 2026-09-30 08:13 UTCVendor advisory
  39. 2026-09-29 05:48 UTCVendor advisory
  40. 2026-09-29 01:55 UTCVendor advisory
  41. 2026-09-28 21:38 UTCEG score recompute
  42. 2026-09-28 21:38 UTCVendor advisory
  43. 2026-09-28 16:00 UTCEG score recompute
  44. 2026-09-28 16:00 UTCVendor advisory
  45. 2026-09-28 13:51 UTCEPSS rescore
  46. 2026-09-28 11:53 UTCVendor advisory
  47. 2026-09-28 07:49 UTCVendor advisory
  48. 2026-09-28 03:56 UTCVendor advisory
  49. 2026-09-28 00:03 UTCVendor advisory
  50. 2026-09-27 19:54 UTCVendor advisory
  51. 2026-09-27 15:57 UTCEG score recompute
  52. 2026-09-27 15:57 UTCVendor advisory
  53. 2026-09-27 10:59 UTCVendor advisory
  54. 2026-09-27 06:53 UTCVendor advisory
  55. 2026-09-27 03:00 UTCEG score recompute
  56. 2026-09-27 03:00 UTCVendor advisory
  57. 2026-09-26 15:59 UTCEPSS rescore
  58. 2026-09-25 12:21 UTCVendor advisory
  59. 2026-09-25 08:28 UTCVendor advisory
  60. 2026-09-25 04:34 UTCVendor advisory
  61. 2026-09-25 00:41 UTCVendor advisory
  62. 2026-09-24 19:33 UTCVendor advisory
  63. 2026-09-24 15:39 UTCEG score recompute
  64. 2026-09-24 15:39 UTCVendor advisory
  65. 2026-09-24 11:42 UTCVendor advisory
  66. 2026-09-24 07:50 UTCVendor advisory
  67. 2026-09-24 03:57 UTCVendor advisory
  68. 2026-09-23 23:58 UTCVendor advisory
  69. 2026-09-23 20:04 UTCEG score recompute
  70. 2026-09-23 20:04 UTCVendor advisory
  71. 2026-09-23 17:54 UTCEPSS rescore
  72. 2026-09-23 15:13 UTCVendor advisory
  73. 2026-09-23 11:21 UTCVendor advisory
  74. 2026-09-23 07:28 UTCVendor advisory
  75. 2026-09-23 03:36 UTCVendor advisory

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Frequently asked(5)

What is CVE-2026-63385?
CVE-2026-63385 is a critical vulnerability published on August 20, 2026. Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has two HTTP parsing weaknesses in http.c. evhttpdecodeuriinternal decodes percent-encoded %00 bytes into literal NUL characters, which can cause downstream C string operations to truncate a path and bypass…
When was CVE-2026-63385 disclosed?
CVE-2026-63385 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-2026-63385 actively exploited?
CVE-2026-63385 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (44th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-63385?
CVE-2026-63385 has a CVSS base score of 9.2 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-63385?
A fix for CVE-2026-63385 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-63385 are linked in the Vendor Advisories panel on this page.

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