CVE-2026-63382

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: 0.6%, top 55% 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 — 3 sources updated this weekElevated
9.2EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.2Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, the libevent evhttp parser in http.c inconsistently handles duplicate Transfer-Encoding headers, comma-separated Transfer-Encoding values, and bare line feeds in chunked framing. evhttp_find_header can select only the first header, evhttp_check_transfer_encoding_ was absent so the previous whole-string comparison fails to recognize valid lists ending in chunked, and evhttp_handle_chunked_read uses EVBUFFER_EOL_CRLF rather than EVBUFFER_EOL_CRLF_STRICT, accepting bare LF chunk terminators. When libevent is deployed behind a proxy that frames the same request differently, an unauthenticated remote attacker can desynchronize request boundaries and smuggle a second request, potentially bypassing access controls or poisoning caches. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.

CVSS v3
9.2
EG Score
9.2(medium)
EG Risk
72(Attend)
EG Risk 72/100SSVC: Attend

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%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
45%
KEV
Not listed

Published

August 20, 2026

Last Modified

August 20, 2026

Advisory Details (7)

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 ac38703b2d31 (libevent/libevent)

Patch available: libevent/libevent release-2.1.13-stable (contains commit ac38703b2d31)

https://github.com/libevent/libevent/commit/ac38703b2d312200c4f967f02936af0118d384a0
github_commit Patch Available

commit 83ba67373032 (libevent/libevent)

Patch available: libevent/libevent release-2.2.2-alpha (contains commit 83ba67373032)

https://github.com/libevent/libevent/commit/83ba67373032334559b82409db035dd8c3cc1660
github_commit Patch Available

commit 5119ceb00557 (libevent/libevent)

Patch available: libevent/libevent release-2.2.2-alpha (contains commit 5119ceb00557)

https://github.com/libevent/libevent/commit/5119ceb00557bf007f9065709e852686f3c0bb6e
github_commit Patch Available

commit 10abb34b8dc3 (libevent/libevent)

Patch available: libevent/libevent release-2.1.13-stable (contains commit 10abb34b8dc3)

https://github.com/libevent/libevent/commit/10abb34b8dc3e1184de315dd261ce4b77563cda6
github Patch Available🟡 PoC Available

libevent evhttp: Multiple HTTP Parser Bugs Enable Request Smuggling · Advisory · libevent/libevent · GitHub

https://github.com/libevent/libevent/security/advisories/GHSA-q39v-w2g7-gr8j

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 13× 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. 2026-08-25 16:58 UTCEG score recompute
  2. 2026-08-25 13:49 UTCEPSS rescore
  3. 2026-08-24 17:35 UTCEG score recompute
  4. 2026-08-24 09:50 UTCEG score recompute
  5. 2026-08-23 02:38 UTCEG score recompute
  6. 2026-08-23 00:19 UTCEPSS rescore
  7. 2026-08-22 03:21 UTCEG score recompute
  8. 2026-08-21 23:49 UTCEPSS rescore
  9. 2026-08-20 20:20 UTCEG score recompute
  10. 2026-08-20 19:37 UTCEG score recompute
  11. 2026-08-20 18:17 UTCEG score recompute
  12. 2026-08-20 17:57 UTCEG score recompute
  13. 2026-08-20 17:56 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-63382?
CVE-2026-63382 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, the libevent evhttp parser in http.c inconsistently handles duplicate Transfer-Encoding headers, comma-separated Transfer-Encoding values, and bare line feeds in chunked framing. evhttpfindheader can select only the first…
When was CVE-2026-63382 disclosed?
CVE-2026-63382 was first published in the National Vulnerability Database on August 20, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-63382 actively exploited?
CVE-2026-63382 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 54.5% of all scored CVEs.
What is the CVSS score of CVE-2026-63382?
CVE-2026-63382 has a CVSS v3 base score of 9.2 (NVD).
How do I remediate CVE-2026-63382?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-63382, 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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