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

Advisory record · `GHSA-24cc-9352-h2pg`

- **Identifiers:** `GHSA-24cc-9352-h2pg` · `CVE-2026-104266`
- **State:** Confirmed
- **Severity:** CVSS 6.5 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-835](https://cwe.mitre.org/data/definitions/835.html)
- **Tags:** [Denial of service](https://agentprime.io/advisories/tag/dos.md)
- **Published:** 15 Oct 2026
- **Updated:** 15 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 15 Oct 2026, 20:16 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `tinytag` (PyPI): affected `>=2.0.0, <2.3.0`; fixed in `2.3.0`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> The tinytag package, versions 2.0.0 up to but not including 2.3.0, can enter an infinite loop when parsing certain M4A files that contain a sub-atom with a size of zero inside a \`----\` atom. An attacker who can supply such a file to a program that reads it with tinytag can cause a denial of service. Upgrade to tinytag 2.3.0, which fixes the issue; the source lists no workarounds.

Written 1 Nov 2026.

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 6.5 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0033, the 26th percentile, on 7 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:08 UTC: First seen by agentprime
- 31 Oct 2026, 14:08 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-24cc-9352-h2pg)

## Sources

- [GitHub Advisory Database: GHSA-24cc-9352-h2pg](https://github.com/advisories/GHSA-24cc-9352-h2pg)
- [OSV: GHSA-24cc-9352-h2pg](https://osv.dev/vulnerability/GHSA-24cc-9352-h2pg)
- <https://github.com/tinytag/tinytag/security/advisories/GHSA-24cc-9352-h2pg>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-104266>
- <https://github.com/tinytag/tinytag/pull/326>
- <https://github.com/tinytag/tinytag/commit/9ada221ba44990cb02cd9002d992186e037b515e>
- <https://github.com/tinytag/tinytag>
- <https://github.com/tinytag/tinytag/releases/tag/2.3.0>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-24cc-9352-h2pg>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-24cc-9352-h2pg/>. Everything for agents: <https://agentprime.io/llms.txt>.