HOMEVULNERABILITIESCVE-2026-40560
HIGH

CVE-2026-40560

CWE-444Published: April 29, 2026· Updated: Apr 30, 2026

7.5
CVSS v3.1
EPSS:0.03%probability of exploitation in 30 daysPercentile:8.7th

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.

NVD Source

Technical Analysis

CVE-2026-40560 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityNone
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
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All References (4)

→
https://datatracker.ietf.org/doc/html/rfc7230#section-3.3.3
→
https://github.com/miyagawa/Starman/commit/ced205f0805027e9d9c0731f8c40b104220604ed.patch
→
https://metacpan.org/release/MIYAGAWA/Starman-0.4018/changes
→
http://www.openwall.com/lists/oss-security/2026/04/29/1

Quick Facts

CVE IDCVE-2026-40560
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-444
CISA KEVNo
EPSS (30d)0.03%
PublishedApr 29, 2026

Related CVEs (CWE-444)

CVE-2026-42581
9.8
CVE-2026-41873
9.8
CVE-2026-9170
9.8
CVE-2026-2833
9.3
CVE-2026-2835
9.3
CVE-2026-28368
9.1

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-40560 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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