Starlet versions through 0.31 for Perl allows HTTP Request Smuggling via Improper Header Precedence
Summary
| CVE | CVE-2026-40561 |
|---|---|
| State | PUBLISHED |
| Assigner | CPANSec |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-03 01:15:58 UTC |
| Updated | 2026-05-03 05:15:58 UTC |
| 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. |
Risk And Classification
Problem Types: CWE-444 | CWE-444 CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| datatracker.ietf.org/doc/html/rfc7230 | 9b29abf9-4ab0-4765-b253-1875cd9b441e | datatracker.ietf.org | |
| github.com/kazuho/Starlet/commit/a7d5dfd1862aafa43e5eaca0fdb6acf4cc15b2d... | 9b29abf9-4ab0-4765-b253-1875cd9b441e | github.com | |
| www.openwall.com/lists/oss-security/2026/05/03/1 | af854a3a-2127-422b-91ae-364da2661108 | www.openwall.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: CPANSec (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-04-12T00:00:00.000Z | Issue identified |
| CNA | 2026-04-28T00:00:00.000Z | Maintainer notified |
| CNA | 2026-05-02T00:00:00.000Z | Determined that the issue was already public on GitHub |
Workarounds
CNA: Migrate to Starman 0.4018 or later which has fixed this issue or apply the patch.
There are currently no legacy QID mappings associated with this CVE.