Vulnerability · Published Apr 28, 2026 · Assigned by CPANSec
CVE-2026-40560Starman versions before 0.4018 for Perl allows HTTP Request Smuggling via Improper Header Precedence
High 7.5
In plain English
A high-severity security flaw in Starman from MIYAGAWA. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 42% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | starman | no fix listed | DEBIAN-CVE-2026-40560 |
| Debian:13 | starman | 0.4018-0+deb13u1 | DEBIAN-CVE-2026-40560 |
| Debian:14 | starman | 0.4018-1 | DEBIAN-CVE-2026-40560 |
| Ubuntu:22.04:LTS | starman | no fix listed | UBUNTU-CVE-2026-40560 |
| Ubuntu:24.04:LTS | starman | no fix listed | UBUNTU-CVE-2026-40560 |
| Ubuntu:25.10 | starman | no fix listed | UBUNTU-CVE-2026-40560 |
| Ubuntu:26.04:LTS | starman | no fix listed | UBUNTU-CVE-2026-40560 |
| Ubuntu:26.10 | starman | no fix listed | UBUNTU-CVE-2026-40560 |
Affected products (as reported)
Weakness: CWE-444 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N