CVE-2026-63384

HIGHPre-NVD 8.78.7—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 68% 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
8.7EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.7Exploit: 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 has an incorrect integer conversion in event_tagging.c when evtag_unmarshal_header uses evtag_decode_int to decode an attacker-controlled uint32 payload length and returns it as a signed int. Values above INT_MAX become negative or truncated, and evtag_unmarshal_string can use the converted value in allocation sizing, producing a wrapped large allocation request and denial of service. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

CVSS v3
8.7
EG Score
8.7(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
Severity87% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
32%
KEV
Not listed

Published

August 20, 2026

Last Modified

September 9, 2026

Advisory Details (5)

Auto-updated Aug 20, 2026
🔬 Proof of concept available. 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 5e3c6ebe342b (libevent/libevent)

Patch available: libevent/libevent release-2.1.13-stable (contains commit 5e3c6ebe342b)

https://github.com/libevent/libevent/commit/5e3c6ebe342b34c5a9bcf48e9a32ad6708b9c416
github_commit Patch Available

commit 109c16499282 (libevent/libevent)

Patch available: libevent/libevent release-2.2.2-alpha (contains commit 109c16499282)

https://github.com/libevent/libevent/commit/109c16499282959d70f56ec3baf4c8b1e6646bda
github Patch Available🟡 PoC Available

`evtag_unmarshal_header()` decodes a wire `uint32` length into a signed `int` return value. · Advisory · libevent/libevent · GitHub

https://github.com/libevent/libevent/security/advisories/GHSA-45c6-qx49-89m8

Vendor Advisories for CVE-2026-63384(1)

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

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibevent-pthreads-2.0-5 (2.0.21-stable-2ubuntu0.16.04.1+esm1) @ xenial2026-09-19ubuntu
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-2.1.12-19.1.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

(4)

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 25× in last 7d / 93× 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 16:50 UTCEG score recompute
  2. 2026-09-19 16:50 UTCVendor advisory
  3. 2026-09-19 05:57 UTCEG score recompute
  4. 2026-09-19 05:57 UTCVendor advisory
  5. 2026-09-18 19:28 UTCEPSS rescore
  6. 2026-09-18 19:04 UTCVendor advisory
  7. 2026-09-18 08:11 UTCVendor advisory
  8. 2026-09-17 21:19 UTCEG score recompute
  9. 2026-09-17 21:19 UTCVendor advisory
  10. 2026-09-17 06:54 UTCVendor advisory
  11. 2026-09-16 20:02 UTCEG score recompute
  12. 2026-09-16 20:02 UTCVendor advisory
  13. 2026-09-16 14:08 UTCEPSS rescore
  14. 2026-09-16 06:53 UTCEG score recompute
  15. 2026-09-16 06:53 UTCVendor advisory
  16. 2026-09-16 05:15 UTCEPSS rescore
  17. 2026-09-15 20:01 UTCVendor advisory
  18. 2026-09-15 09:09 UTCEG score recompute
  19. 2026-09-15 09:09 UTCVendor advisory
  20. 2026-09-14 22:17 UTCVendor advisory
  21. 2026-09-14 11:25 UTCVendor advisory
  22. 2026-09-14 00:33 UTCEG score recompute
  23. 2026-09-14 00:33 UTCVendor advisory
  24. 2026-09-13 13:41 UTCVendor advisory
  25. 2026-09-13 02:49 UTCVendor advisory
Show 71 more
  1. 2026-09-12 15:57 UTCEG score recompute
  2. 2026-09-12 15:57 UTCVendor advisory
  3. 2026-09-12 05:05 UTCVendor advisory
  4. 2026-09-11 18:13 UTCEG score recompute
  5. 2026-09-11 18:13 UTCVendor advisory
  6. 2026-09-11 14:53 UTCEPSS rescore
  7. 2026-09-11 09:37 UTCEPSS rescore
  8. 2026-09-11 07:21 UTCVendor advisory
  9. 2026-09-10 20:29 UTCVendor advisory
  10. 2026-09-10 09:37 UTCEG score recompute
  11. 2026-09-10 09:37 UTCVendor advisory
  12. 2026-09-09 22:34 UTCVendor advisory
  13. 2026-09-09 13:05 UTCVendor advisory
  14. 2026-09-09 01:56 UTCEG score recompute
  15. 2026-09-09 01:56 UTCVendor advisory
  16. 2026-09-08 22:01 UTCEPSS rescore
  17. 2026-09-08 02:24 UTCEG score recompute
  18. 2026-09-08 02:24 UTCVendor advisory
  19. 2026-09-07 16:01 UTCEPSS rescore
  20. 2026-09-07 15:33 UTCVendor advisory
  21. 2026-09-07 04:21 UTCVendor advisory
  22. 2026-09-06 17:25 UTCEG score recompute
  23. 2026-09-06 17:25 UTCVendor advisory
  24. 2026-09-06 13:47 UTCEPSS rescore
  25. 2026-09-06 06:32 UTCVendor advisory
  26. 2026-09-05 19:40 UTCEG score recompute
  27. 2026-09-05 19:40 UTCVendor advisory
  28. 2026-09-05 15:31 UTCEPSS rescore
  29. 2026-09-05 08:49 UTCVendor advisory
  30. 2026-09-04 21:57 UTCEG score recompute
  31. 2026-09-04 21:57 UTCVendor advisory
  32. 2026-09-04 11:04 UTCEG score recompute
  33. 2026-09-04 11:04 UTCVendor advisory
  34. 2026-09-04 05:07 UTCEPSS rescore
  35. 2026-09-04 00:05 UTCVendor advisory
  36. 2026-09-03 13:06 UTCVendor advisory
  37. 2026-09-03 02:05 UTCVendor advisory
  38. 2026-09-02 15:12 UTCEG score recompute
  39. 2026-09-02 15:12 UTCVendor advisory
  40. 2026-09-02 14:12 UTCEPSS rescore
  41. 2026-09-02 04:18 UTCVendor advisory
  42. 2026-09-01 17:25 UTCEG score recompute
  43. 2026-09-01 17:25 UTCVendor advisory
  44. 2026-09-01 13:54 UTCEPSS rescore
  45. 2026-09-01 06:32 UTCEG score recompute
  46. 2026-09-01 06:32 UTCVendor advisory
  47. 2026-09-01 04:40 UTCEPSS rescore
  48. 2026-08-31 19:38 UTCVendor advisory
  49. 2026-08-31 08:46 UTCVendor advisory
  50. 2026-08-30 21:18 UTCEG score recompute
  51. 2026-08-30 21:18 UTCVendor advisory
  52. 2026-08-30 19:17 UTCEPSS rescore
  53. 2026-08-30 10:26 UTCEG score recompute
  54. 2026-08-30 01:22 UTCEPSS rescore
  55. 2026-08-29 01:28 UTCEG score recompute
  56. 2026-08-28 21:42 UTCEPSS rescore
  57. 2026-08-27 15:40 UTCEG score recompute
  58. 2026-08-27 14:25 UTCEPSS rescore
  59. 2026-08-26 17:53 UTCEG score recompute
  60. 2026-08-26 14:46 UTCEPSS rescore
  61. 2026-08-25 19:54 UTCEG score recompute
  62. 2026-08-25 13:49 UTCEPSS rescore
  63. 2026-08-24 22:10 UTCEG score recompute
  64. 2026-08-24 11:18 UTCEG score recompute
  65. 2026-08-23 02:42 UTCEG score recompute
  66. 2026-08-23 00:19 UTCEPSS rescore
  67. 2026-08-22 04:58 UTCEG score recompute
  68. 2026-08-21 23:49 UTCEPSS rescore
  69. 2026-08-20 18:17 UTCEG score recompute
  70. 2026-08-20 17:57 UTCEG score recompute
  71. 2026-08-20 17:56 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-63384?
CVE-2026-63384 is a high vulnerability published on August 20, 2026. Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an incorrect integer conversion in eventtagging.c when evtagunmarshalheader uses evtagdecodeint to decode an attacker-controlled uint32 payload length and returns it as a signed int. Values above INTMAX become…
When was CVE-2026-63384 disclosed?
CVE-2026-63384 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-2026-63384 actively exploited?
CVE-2026-63384 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 67.7% of all scored CVEs.
What is the CVSS score of CVE-2026-63384?
CVE-2026-63384 has a CVSS v3 base score of 8.7 (NVD).
How do I remediate CVE-2026-63384?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63384, 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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