# CVE-2026-115866: starlet: Starlet versions from 0.20 before 0.33 for Perl allow CPU exhaustion via regular expression backtracking when decodin...

CVE-2026-115866 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-115866, released November 3, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-115866
- Priority: High
- CVSS: 7.5 (high)
- EPSS: 0.0038
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 30, 2026

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | perl-Starlet Fedora 43 | 0.33-1.fc43 | [FEDORA-2026-092670EC3E](https://patchblox.com/security/data/fix/linux/fedora-2026-092670ec3e.md) | Nov 10, 2026 |
| Linux | starlet Debian 14 | 0.33-1 | [DEBIAN-CVE-2026-115866](https://patchblox.com/security/data/fix/linux/debian-cve-2026-115866.md) | Nov 3, 2026 |

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Data as of 2026-11-10T07:50:38Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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