CVE-2026-40560 Starman versions before 0.4018 for Perl allows HTTP Request Smuggling via Improper Header Precedence
Starman allows HTTP request smuggling by mishandling conflicting headers, enabling attackers to bypass security controls via reverse proxies.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-40560?
CVE-2026-40560 is a high-severity vulnerability in MIYAGAWA Starman, published on 28 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-444
Which versions are affected by CVE-2026-40560?
It affects 1 product.
Linux distribution packages (1)
perl-Starman openSUSE:Tumbleweed | All versions | 0.4018-1.1 |
Products include Miyagawa Starman.
How do I fix CVE-2026-40560?
Upgrade to a fixed version.
Is CVE-2026-40560 being exploited?
There is no known exploitation of CVE-2026-40560 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-40560, GHSA-gwjf-hg8j-jwvr, MGASA-2026-0119, UBUNTU-CVE-2026-40560, openSUSE-SU-2026:10757-1.