# CVE-2026-63382

## Summary

- **CVE ID:** CVE-2026-63382
- **Severity:** CRITICAL
- **CVSS Score:** 9.2 (CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:L/SI:L/SA:N)
- **CWE:** CWE-444
- **Published:** Aug 20, 2026
- **Last Modified:** Aug 20, 2026

## Description

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.

## Affected Products

- libevent — libevent (>= 2.2.0-alpha, < 2.2.2-alpha)
- libevent — libevent (< 2.1.13)

## References

- [CNA](https://github.com/libevent/libevent/security/advisories/GHSA-q39v-w2g7-gr8j)
- [CNA](https://github.com/libevent/libevent/commit/10abb34b8dc3e1184de315dd261ce4b77563cda6)
- [CNA](https://github.com/libevent/libevent/commit/5119ceb00557bf007f9065709e852686f3c0bb6e)
- [CNA](https://github.com/libevent/libevent/commit/83ba67373032334559b82409db035dd8c3cc1660)
- [CNA](https://github.com/libevent/libevent/commit/ac38703b2d312200c4f967f02936af0118d384a0)
- [CNA](https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable)
- [CNA](https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.59%
- **EPSS Percentile:** 46.0

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-09._