CVE-2026-63382
CRITICALDescription
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.
How to fix
This Ubuntu release reached end-of-life on 2019-04-02.
This Ubuntu release reached end-of-life on 2021-04-02.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2025-05-31. Extended security maintenance is available until 2030-04-02.
This Ubuntu release reached end-of-life on 2019-04-02.
This Ubuntu release reached end-of-life on 2021-04-02.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2025-05-31. Extended security maintenance is available until 2030-04-02.
This Ubuntu release reached end-of-life on 2019-04-02.
This Ubuntu release reached end-of-life on 2021-04-02.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2025-05-31. Extended security maintenance is available until 2030-04-02.
This Ubuntu release reached end-of-life on 2019-04-02.
This Ubuntu release reached end-of-life on 2021-04-02.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2025-05-31. Extended security maintenance is available until 2030-04-02.
This Ubuntu release reached end-of-life on 2019-04-02.
This Ubuntu release reached end-of-life on 2021-04-02.
This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.
This Ubuntu release reached end-of-life on 2025-05-31. Extended security maintenance is available until 2030-04-02.
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v4 Vector
Exploitability
Impact
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Exploit Intelligence
Moderate risk: more likely to be exploited than 46% of all known CVEs.
References
Related Vulnerabilities
Other CWE-444 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2022-22536 | Critical | 10.0 | 98% | KEV | - |
| CVE-2025-61884 | High | 7.5 | 96% | KEV + Ransom | - |
| CVE-2020-9490 | High | 7.5 | 89% | - | Fix |
| CVE-2023-41265 | Critical | 9.6 | 88% | KEV + Ransom | - |
| CVE-2023-25690 | Critical | 9.8 | 85% | - | Fix |
| CVE-2022-32214 | Medium | 6.5 | 82% | - | Fix |
Common questions
How do I fix CVE-2026-63382?
Published advisories record a fix for 17 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2026-63382 being actively exploited?
Not that we know of. CVE-2026-63382 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.59% is the estimated probability that it will be exploited in the next 30 days. That is higher than 46% of all scored CVEs.
How severe is CVE-2026-63382?
CVE-2026-63382 has a CVSS v4 base score of 9.2, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2026-63382 affect?
Published advisories record a fix for libevent (Debian), libevent (Rocky), libevent (Red Hat / RHEL), libevent (Ubuntu), and 13 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2026-63382
Markdown
[](https://tridentstack.com/cve/CVE-2026-63382)HTML
<a href="https://tridentstack.com/cve/CVE-2026-63382"><img src="https://tridentstack.com/cve/badge/CVE-2026-63382.svg" alt="CVE-2026-63382"></a>Check your Linux endpoints for this class of vulnerability
TridentStack Control continuously scans Linux endpoints for known vulnerabilities and deploys the fixes from the same console. 200 endpoints free forever, no credit card.
This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-09.