CVE-2026-40561

MEDIUM

5.3

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.

CVE Details

CVSS v3.1 Score5.3

SeverityMEDIUM

CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Attack VectorNETWORK

ComplexityLOW

Privileges RequiredNONE

User InteractionNONE

Published5/3/2026

Last Modified5/4/2026

Sourcenvd

Honeypot Sightings0

Weaknesses (CWE)

CWE-444

References

https://datatracker.ietf.org/doc/html/rfc7230#section-3.3.3(9b29abf9-4ab0-4765-b253-1875cd9b441e)

https://github.com/kazuho/Starlet/commit/a7d5dfd1862aafa43e5eaca0fdb6acf4cc15b2d0.patch(9b29abf9-4ab0-4765-b253-1875cd9b441e)

http://www.openwall.com/lists/oss-security/2026/05/03/1(af854a3a-2127-422b-91ae-364da2661108)

IOC Correlations

No correlations recorded

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