CVE-2026-40560

Name: CVE-2026-40560
Creator: NVD / NIST
Published: 2026-04-29T00:16:03.927+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 0.49%

Last modified Jun 17, 2026

CVE-2026-40560 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. Starman versions before 0.4018 for Perl allows HTTP Request Smuggling via Improper Header Precedence. Starman 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.. EPSS estimates a 0.49% chance of exploitation in the next 30 days.

Description

Starman versions before 0.4018 for Perl allows HTTP Request Smuggling via Improper Header Precedence. Starman 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.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

0.49%

38.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-444

Affected Software

Vendor	Product	Versions
Miyagawa	Starman	< 0.4018

References

https://datatracker.ietf.org/doc/html/rfc7230#section-3.3.3Third Party Advisory
https://github.com/miyagawa/Starman/commit/ced205f0805027e9d9c0731f8c40b104220604ed.patchPatch, Third Party Advisory
https://metacpan.org/release/MIYAGAWA/Starman-0.4018/changesProduct, Release Notes
http://www.openwall.com/lists/oss-security/2026/04/29/1Mailing List, Third Party Advisory

Timeline

Published: Apr 29, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-40560?

How severe is CVE-2026-40560?

CVE-2026-40560 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.49% probability of exploitation in the next 30 days.

How do I fix CVE-2026-40560?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-40560?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST