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Fencer Intel
high 7.5

CVE-2026-115866 json

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies

published 10d ago modified 3d ago also EUVD-2026-113907

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 32%
public exploits
0
none known

Summary

Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decoding chunked request bodies.

A chunk-size line is matched as a run of hex digits, then .* and a CRLF. A run followed by a bare LF and then a CRLF can never match, and the engine retries the match once for each digit, so the time taken grows with the square of the run length. Nothing limits the length of the run, which can span several reads.

A remote attacker can occupy a worker for about a minute of CPU time with one 128 KiB request, before the application is called.

Patch / fix

  • cpan Starlet 0.33
  • starlet Debian 14 0.33-1

debian advisories DEBIAN-CVE-2026-115866

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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-2026-115866 updated cvss 7.5

perl-starlet: Starlet: Denial of Service via regular expression backtracking

  • 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
3d ago

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-09).

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:N/I:N/A:H
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • cpan Starlet

Classification

Weakness
  • CWE-1333 Inefficient Regular Expression Complexity

References

Sources

Fencer Intel 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.