CVE-2026-40561

MEDIUM EPSS 29.6%
Published May 3, 20261mo ago · Modified Jun 17, 20261w ago
5.3 CVSS 3.1
Medium
Find Similar
Published May 3, 2026 1mo ago
Last Modified Jun 17, 2026 1w ago

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 Details

Base Score
5.3
Exploitability
3.9
Impact
1.4
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity Low
Availability None

Threat Intelligence

EPSS Exploit Probability
29.6% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-444

Affected Products 1

VendorProductVersionRange
kazuhostarlet* ≤0.31

References 4

  • openwall.com http://www.openwall.com/lists/oss-security/2026/05/03/1
    Mailing ListThird Party Advisory
  • datatracker.ietf.org https://datatracker.ietf.org/doc/html/rfc7230#section-3.3.3
    Third Party Advisory
  • github.com https://github.com/kazuho/Starlet/commit/a7d5dfd1862aafa43e5eaca0fdb6acf4cc15b2d0.patch
    Patch
  • metacpan.org https://metacpan.org/release/KAZUHO/Starlet-0.32/changes

Remediation

  • github.com https://github.com/kazuho/Starlet/commit/a7d5dfd1862aafa43e5eaca0fdb6acf4cc15b2d0.patch
    Patch