# CVE-2026-116268: libmime-tools-perl: MIME::Field::ParamVal versions before 5.521 for Perl allow CPU exhaustion via unclosed comments in header parameters

CVE-2026-116268 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-116268, released November 3, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-116268
- Priority: High
- CVSS: 7.5 (high)
- EPSS: 0.0029
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 22, 2026

## Description

MIME::Field::ParamVal versions before 5.521 for Perl allow CPU exhaustion via unclosed comments in header parameters.  The comment pattern used to parse Content-Type and Content-Disposition parameters scans from each "(" to the next ")". In a field with no ")", every "(" scans to the end of the header and fails, so parsing takes time quadratic in the header length. The field is parsed again on each attribute lookup, several times per MIME entity.  A 40 KB header takes about 7 seconds to parse once.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libmime-tools-perl Debian 14 | 5.522-1 | [DEBIAN-CVE-2026-116268](https://patchblox.com/security/data/fix/linux/debian-cve-2026-116268.md) | Nov 3, 2026 |
| Linux | perl-MIME-tools Fedora 43 | 5.522-1.fc43 | [FEDORA-2026-A415B3BF48](https://patchblox.com/security/data/fix/linux/fedora-2026-a415b3bf48.md) | Nov 7, 2026 |
| Linux | perl-MIME-tools opensuse-leap 16.0 | 5.522.0-bp160.1.1 | [OPENSUSE-SU-2026:22226-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-22226-1.md) | Nov 7, 2026 |

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Data as of 2026-11-09T13:31:49Z 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 Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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