VulnerabilityModified
CVE-2026-40561
Starlet versions through 0.31 for Perl allows HTTP Request Smuggling via Improper Header Precedence.
MEDIUM 5.3EPSS 0.36%
Does this matter?
Lower severity and a low EPSS score (0.36%). Track it; it rarely justifies an emergency change on its own.
Description
Starlet versions through 0.31 for Perl allows HTTP Request Smuggling via Improper Header Precedence. Starlet incorrectly prioritizes "Content-Length" over "Transfer-Encoding: chunked" when both headers are present in an HTTP request. Per RFC 7230 3.3.3, Transfer-Encoding must take precedence. An attacker could exploit this to smuggle malicious HTTP requests via a front-end reverse proxy.
- CVSS 3.1
- 5.3 MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- EPSS
- 0.36% probability · 30th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-444
- Affected
- kazuho/starlet
- Source
- 9b29abf9-4ab0-4765-b253-1875cd9b441e
References
- https://datatracker.ietf.org/doc/html/rfc7230#section-3.3.3Third Party Advisory
- https://github.com/kazuho/Starlet/commit/a7d5dfd1862aafa43e5eaca0fdb6acf4cc15b2d0.patchPatch
- https://metacpan.org/release/KAZUHO/Starlet-0.32/changes
- http://www.openwall.com/lists/oss-security/2026/05/03/1Mailing List, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.