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Fencer Vulns
high 7.5

CVE-2026-40560 json

Starman versions before 0.4018 for Perl allows HTTP Request Smuggling via Improper Header Precedence

published 2026-04-28 6 mo ago modified 2026-07-24 3 mo ago also EUVD-2026-26189

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

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.

Patch / fix

  • MIYAGAWA Starman 0.4018
  • starman Debian 13 0.4018-0+deb13u1
  • starman Debian 14 0.4018-1

debian advisories DEBIAN-CVE-2026-40560

  • perl-Starman openSUSE Tumbleweed 0.4018-1.1

opensuse advisories openSUSE-SU-2026:10757-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-40560 updated cvss 8.8

Starman: Starman: HTTP Request Smuggling via improper header precedence

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
6 mo ago

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

  • MIYAGAWA Starman

Classification

Weakness
  • CWE-444 Inconsistent Interpretation of HTTP Requests

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.