CVE-2026-40561
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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| debian | bookworm | affected | |
| debian | bullseye | affected | |
| debian | forky | fixed | 0.31-3 |
| debian | sid | fixed | 0.31-3 |
| debian | trixie | fixed | 0.31-2+deb13u1 |
Application impact
| Vendor | Product | Versions | Fixed |
|---|---|---|---|
| kazuho | starlet | {"endIncluding":"0.31"} | |
References
- https://datatracker.ietf.org/doc/html/rfc7230#section-3.3.3
- https://github.com/kazuho/Starlet/commit/a7d5dfd1862aafa43e5eaca0fdb6acf4cc15b2d0.patch
- https://metacpan.org/release/KAZUHO/Starlet-0.32/changes
- http://www.openwall.com/lists/oss-security/2026/05/03/1
- https://security-tracker.debian.org/tracker/CVE-2026-40561
CWEs
CWE-444
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.