CVE-2026-63388

HIGHPre-NVD 8.48.4—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 96% 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
8.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.4Exploit: 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 a heap out-of-bounds write in bufferevent_sock.c when bufferevent_socket_set_conn_address_ copies a kernel-supplied AF_UNIX peer address into bufferevent_private.conn_address. Release builds compiled with NDEBUG disable the EVUTIL_ASSERT length guard, and the evhttp accept path can pass a 110-byte sockaddr from accept() into the 28-byte field. An unauthenticated local peer able to connect to an AF_UNIX listener can overwrite the adjacent dns_request pointer and heap data, causing memory corruption with confidentiality, integrity, and availability impact. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

CVSS v3
8.4
EG Score
8.4(medium)
EG Risk
38(Track)
EG Risk 38/100SSVC: 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
Severity84% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
4%
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 ef38f926e9cd (libevent/libevent)

Patch available: libevent/libevent release-2.1.13-stable (contains commit ef38f926e9cd)

https://github.com/libevent/libevent/commit/ef38f926e9cd1f082416c6fff13587bc1f431d72
github_commit Patch Available

commit 52057cb33d0c (libevent/libevent)

Patch available: libevent/libevent release-2.2.2-alpha (contains commit 52057cb33d0c)

https://github.com/libevent/libevent/commit/52057cb33d0c20c0a0453fbabe6c0c96854931b9
github Patch Available🟡 PoC Available

Heap out-of-bounds write in bufferevent_socket_set_conn_address_ reachable via AF_UNIX accept · Advisory · libevent/libevent · GitHub

https://github.com/libevent/libevent/security/advisories/GHSA-cvq5-vrvr-j338

Vendor Advisories for CVE-2026-63388(1)

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

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatlibevent-0:2.1.8-11.el8_102026-09-16redhat
redhatlibevent-0:2.1.13-1.el9_82026-09-16redhat
redhatlibevent-0:2.1.13-1.el10_22026-09-16redhat
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(2)

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

Additional Vendor Advisories

(3)

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 / 90× 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 20:18 UTCEG score recompute
  2. 2026-09-19 20:18 UTCVendor advisory
  3. 2026-09-19 09:04 UTCVendor advisory
  4. 2026-09-18 21:39 UTCEG score recompute
  5. 2026-09-18 21:39 UTCVendor advisory
  6. 2026-09-18 19:28 UTCEPSS rescore
  7. 2026-09-18 09:06 UTCVendor advisory
  8. 2026-09-17 21:52 UTCEG score recompute
  9. 2026-09-17 21:52 UTCVendor advisory
  10. 2026-09-17 10:38 UTCVendor advisory
  11. 2026-09-16 23:17 UTCEG score recompute
  12. 2026-09-16 23:17 UTCVendor advisory
  13. 2026-09-16 14:08 UTCEPSS rescore
  14. 2026-09-16 12:03 UTCEG score recompute
  15. 2026-09-16 12:03 UTCVendor advisory
  16. 2026-09-16 05:15 UTCEPSS rescore
  17. 2026-09-16 00:49 UTCVendor advisory
  18. 2026-09-15 13:26 UTCEG score recompute
  19. 2026-09-15 13:26 UTCVendor advisory
  20. 2026-09-15 02:12 UTCVendor advisory
  21. 2026-09-14 14:57 UTCVendor advisory
  22. 2026-09-14 03:43 UTCEG score recompute
  23. 2026-09-14 03:43 UTCVendor advisory
  24. 2026-09-13 16:29 UTCVendor advisory
  25. 2026-09-13 05:15 UTCVendor advisory
Show 68 more
  1. 2026-09-12 18:01 UTCEG score recompute
  2. 2026-09-12 18:01 UTCVendor advisory
  3. 2026-09-12 06:46 UTCVendor advisory
  4. 2026-09-11 19:30 UTCEG score recompute
  5. 2026-09-11 19:30 UTCVendor advisory
  6. 2026-09-11 09:37 UTCEPSS rescore
  7. 2026-09-11 08:16 UTCVendor advisory
  8. 2026-09-10 21:02 UTCVendor advisory
  9. 2026-09-10 09:48 UTCEG score recompute
  10. 2026-09-10 09:48 UTCVendor advisory
  11. 2026-09-09 22:34 UTCVendor advisory
  12. 2026-09-09 13:14 UTCVendor advisory
  13. 2026-09-09 01:56 UTCEG score recompute
  14. 2026-09-09 01:56 UTCVendor advisory
  15. 2026-09-08 22:01 UTCEPSS rescore
  16. 2026-09-08 02:46 UTCEG score recompute
  17. 2026-09-08 02:46 UTCVendor advisory
  18. 2026-09-07 16:01 UTCEPSS rescore
  19. 2026-09-07 15:33 UTCVendor advisory
  20. 2026-09-07 03:25 UTCVendor advisory
  21. 2026-09-06 15:56 UTCEG score recompute
  22. 2026-09-06 15:56 UTCVendor advisory
  23. 2026-09-06 13:47 UTCEPSS rescore
  24. 2026-09-06 04:42 UTCVendor advisory
  25. 2026-09-05 17:28 UTCEG score recompute
  26. 2026-09-05 17:28 UTCVendor advisory
  27. 2026-09-05 15:31 UTCEPSS rescore
  28. 2026-09-05 06:06 UTCVendor advisory
  29. 2026-09-04 18:49 UTCEG score recompute
  30. 2026-09-04 18:49 UTCVendor advisory
  31. 2026-09-04 07:12 UTCEG score recompute
  32. 2026-09-04 07:12 UTCVendor advisory
  33. 2026-09-04 05:07 UTCEPSS rescore
  34. 2026-09-03 19:44 UTCVendor advisory
  35. 2026-09-03 08:24 UTCVendor advisory
  36. 2026-09-02 21:09 UTCVendor advisory
  37. 2026-09-02 07:09 UTCVendor advisory
  38. 2026-09-01 19:54 UTCEG score recompute
  39. 2026-09-01 19:54 UTCVendor advisory
  40. 2026-09-01 13:54 UTCEPSS rescore
  41. 2026-09-01 08:17 UTCEG score recompute
  42. 2026-09-01 08:17 UTCVendor advisory
  43. 2026-09-01 04:40 UTCEPSS rescore
  44. 2026-08-31 20:56 UTCVendor advisory
  45. 2026-08-31 09:40 UTCVendor advisory
  46. 2026-08-30 22:26 UTCEG score recompute
  47. 2026-08-30 22:26 UTCVendor advisory
  48. 2026-08-30 19:17 UTCEPSS rescore
  49. 2026-08-30 11:13 UTCEG score recompute
  50. 2026-08-30 01:22 UTCEPSS rescore
  51. 2026-08-29 01:28 UTCEG score recompute
  52. 2026-08-28 21:42 UTCEPSS rescore
  53. 2026-08-28 00:45 UTCEG score recompute
  54. 2026-08-27 14:25 UTCEPSS rescore
  55. 2026-08-27 01:59 UTCEG score recompute
  56. 2026-08-26 14:46 UTCEPSS rescore
  57. 2026-08-25 16:17 UTCEG score recompute
  58. 2026-08-25 13:49 UTCEPSS rescore
  59. 2026-08-24 17:49 UTCEG score recompute
  60. 2026-08-23 08:08 UTCEG score recompute
  61. 2026-08-23 00:19 UTCEPSS rescore
  62. 2026-08-22 09:40 UTCEG score recompute
  63. 2026-08-21 23:49 UTCEPSS rescore
  64. 2026-08-21 22:26 UTCEG score recompute
  65. 2026-08-21 22:00 UTCEG score recompute
  66. 2026-08-20 18:17 UTCEG score recompute
  67. 2026-08-20 17:57 UTCEG score recompute
  68. 2026-08-20 17:56 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-63388?
CVE-2026-63388 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 a heap out-of-bounds write in buffereventsock.c when buffereventsocketsetconnaddress copies a kernel-supplied AFUNIX peer address into buffereventprivate.connaddress. Release builds compiled with NDEBUG disable…
When was CVE-2026-63388 disclosed?
CVE-2026-63388 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-2026-63388 actively exploited?
CVE-2026-63388 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 96.1% of all scored CVEs.
What is the CVSS score of CVE-2026-63388?
CVE-2026-63388 has a CVSS v3 base score of 8.4 (NVD).
How do I remediate CVE-2026-63388?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63388, 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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