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% (2nd 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
8.4EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 8.4Exploit: 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 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
8.4HIGHmedium confidence
EG Risk
38
EG Risk 38/100CISA 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
Severity84% × 45%
Exploitation0% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.1%
EPSS %ILE
3rd
KEV
Not listed

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

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

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (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
🔬 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
githubMentions a patch (unverified)🟡 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(12)

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

Patch Availability(12)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibevent-pthreads-2.1-6 (2.1.8-stable-4ubuntu0.1~esm2) @ bionic2026-10-08ubuntu
redhatcert-manager/cert-manager-operator-rhel9:17905898552026-09-28redhat
redhatcert-manager/jetstack-cert-manager-rhel9:17902232792026-09-28redhat
redhatcert-manager/cert-manager-istio-csr-rhel9:17902237192026-09-28redhat
redhatcert-manager/cert-manager-operator-rhel9:17902724262026-09-28redhat
redhatcert-manager/cert-manager-istio-csr-rhel9:17905899142026-09-28redhat
redhatcert-manager/jetstack-cert-manager-rhel9:17905899122026-09-28redhat
redhatrhui5/rhua-rhel9:17902420042026-09-24redhat
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 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(2)

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 19× in last 7d / 97× 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 158 total refreshes for this CVE.

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

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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 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 0.1% probability of exploitation in the next 30 days (3rd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-63388?
CVE-2026-63388 has a CVSS base score of 8.4 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-63388?
A fix for CVE-2026-63388 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-63388 are linked in the Vendor Advisories panel on this page.

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