tinytag: Infinite loop when parsing certain M4A files containing invalid atoms

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-104266: 0.33% estimated exploitation activity in the next 30 days; percentile 26.42 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact An M4A file containing a sub-atom with a size of zero in the ---- atom makes the parser enter an infinite loop, resulting in a denial-of-service for programs reading such files with tinytag. Patches The issue has been fixed in tinytag 2.3.0, by reusing the primary atom parsing code path that contains appropriate size checks. Workarounds No workarounds exist. Users must upgrade to tinytag 2.3.0.

Published by the source

15 Oct 2026, 20:16 UTC

Last modified by the source

15 Oct 2026, 20:30 UTC

Source last checked

26 Oct 2026, 13:55 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-24cc-9352-h2pg

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-24cc-9352-h2pg

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-24cc-9352-h2pg

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# Patch Next advisory brief: CVE-2026-104266

Advisory: tinytag: Infinite loop when parsing certain M4A files containing invalid atoms
IDs: CVE-2026-104266, GHSA-24cc-9352-h2pg
Record: https://patchnext.com/advisories/cve-2026-104266 (revision 3, source checked 26 Oct 2026, 13:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: tinytag 2.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI tinytag: affected >= 2.0.0, < 2.3.0; fixed in 2.3.0

## Suggested inspection (read-only)
- `python -m pip show tinytag`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on tinytag.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-24cc-9352-h2pg (GitHub-reviewed advisory GHSA-24cc-9352-h2pg lists affected ranges: PyPI tinytag >=2.0.0 <2.3.0)
- Verified: https://osv.dev/vulnerability/GHSA-24cc-9352-h2pg (OSV record GHSA-24cc-9352-h2pg lists affected ranges: PyPI tinytag >=2.0.0 <2.3.0 (fixed))

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