CVE-2026-63380

MEDIUMPre-NVD 5.75.7
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This medium-severity CVE scores 5.7 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1% (2nd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Elevated
5.7EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 5.7Exploit: No code on recordExposed services: Not assessed

A fix is available — apply it.

Libevent is an event notification library. Prior to 2.2.2-alpha, libevent can dereference invalid list pointers in ws.c when evws_new_session enters its error path after evhttp_start_ws_ succeeds but bufferevent_enable_locking_ fails. evws_connection_free sees a non-null http_server and unconditionally calls TAILQ_REMOVE even though the session was never inserted into http_server->ws_sessions. A local caller able to induce this allocation or locking failure can crash the process. This issue is fixed in version 2.2.2-alpha.

CVSS v3
5.7
EG Score
5.7MEDIUMmedium confidence
EG Risk
42
EG Risk 42/100

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 (value × EchelonGraph’s weight)
Severity57% × 45%
The EG Score, 5.7 of 10.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.1%
EPSS %ILE
2nd
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

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

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 20, 2026

Last Modified

September 9, 2026

Advisory Details (3)

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 commit Patch Available

commit 825c18bd99f5 (libevent/libevent)

Patch available: libevent/libevent release-2.2.2-alpha (contains commit 825c18bd99f5)

https://github.com/libevent/libevent/commit/825c18bd99f556b59d61200523237f264d5cc734
GitHub advisoryMentions a patch (unverified)

Null Pointer Dereference in `evws_new_session` · Advisory · libevent/libevent · GitHub

https://github.com/libevent/libevent/security/advisories/GHSA-3rpf-frgx-xq34

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 40× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  3. 2026-10-12 15:49 UTCEG score recompute
  4. 2026-10-11 19:33 UTCEG score recompute
  5. 2026-10-11 16:48 UTCEG score recompute
  6. 2026-10-11 14:10 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  9. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  10. 2026-10-09 08:32 UTCEG score recompute
  11. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  12. 2026-10-08 05:22 UTCEG score recompute
  13. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  14. 2026-10-07 03:49 UTCEG score recompute
  15. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  16. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  17. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  18. 2026-10-03 16:47 UTCEG score recompute
  19. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  20. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  21. 2026-10-02 08:32 UTCEG score recompute
  22. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  23. 2026-10-01 08:25 UTCEG score recompute
  24. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  25. 2026-09-30 08:13 UTCEG score recompute
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  1. 2026-09-29 03:19 UTCEG score recompute
  2. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  3. 2026-09-27 03:00 UTCEG score recompute
  4. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  5. 2026-09-25 01:05 UTCEG score recompute
  6. 2026-09-24 00:57 UTCEG score recompute
  7. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  8. 2026-09-22 00:42 UTCEG score recompute
  9. 2026-09-19 00:19 UTCEG score recompute
  10. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  11. 2026-09-18 00:12 UTCEG score recompute
  12. 2026-09-17 00:05 UTCEG score recompute
  13. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  14. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  15. 2026-09-15 23:57 UTCEG score recompute
  16. 2026-09-13 23:43 UTCEG score recompute
  17. 2026-09-12 23:36 UTCEG score recompute
  18. 2026-09-11 23:28 UTCEG score recompute
  19. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  20. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  21. 2026-09-10 22:41 UTCEG score recompute
  22. 2026-09-09 01:56 UTCEG score recompute
  23. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  24. 2026-09-07 21:53 UTCEG score recompute
  25. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  26. 2026-09-06 21:45 UTCEG score recompute
  27. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  28. 2026-09-05 21:37 UTCEG score recompute
  29. 2026-09-05 15:31 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  30. 2026-09-04 21:30 UTCEG score recompute
  31. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  32. 2026-09-02 21:09 UTCEG score recompute
  33. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  34. 2026-09-01 19:54 UTCEG score recompute
  35. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  36. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  37. 2026-08-31 19:04 UTCEG score recompute
  38. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  39. 2026-08-30 18:23 UTCEG score recompute
  40. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  41. 2026-08-29 18:16 UTCEG score recompute
  42. 2026-08-28 21:42 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  43. 2026-08-27 16:44 UTCEG score recompute
  44. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  45. 2026-08-26 16:34 UTCEG score recompute
  46. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  47. 2026-08-25 16:26 UTCEG score recompute
  48. 2026-08-25 15:31 UTCEG score recompute
  49. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  50. 2026-08-24 18:46 UTCEG score recompute
  51. 2026-08-23 18:38 UTCEG score recompute
  52. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  53. 2026-08-22 18:31 UTCEG score recompute
  54. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  55. 2026-08-20 18:17 UTCEG score recompute
  56. 2026-08-20 17:57 UTCEG score recomputeFirst assessed: 5.7 MEDIUM
  57. 2026-08-20 17:56 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-63380?
CVE-2026-63380 is a medium-severity vulnerability; its CVE record was published on August 20, 2026. Libevent is an event notification library. Prior to 2.2.2-alpha, libevent can dereference invalid list pointers in ws.c when evwsnewsession enters its error path after evhttpstartws succeeds but buffereventenablelocking fails. evwsconnectionfree sees a non-null httpserver and unconditionally calls…
When was the CVE record for CVE-2026-63380 published?
The CVE record for CVE-2026-63380 was published on August 20, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 9, 2026; the record at its source may have been updated since.
Is CVE-2026-63380 actively exploited?
CVE-2026-63380 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (2nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-63380?
CVE-2026-63380 has a CVSS base score of 5.7 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-63380?
A fix for CVE-2026-63380 is available: update to the fixed version the vendor names in its advisory.

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