CVE-2026-104266: tinytag: Infinite loop when parsing certain M4A files containing invalid atoms

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-15 · updated 2026-10-21
Weakness: CWE-835

Description

tinytag is a Python library for reading audio file metadata. From 2.0.0 until 2.3.0, an M4A file containing a sub-atom with a size of zero inside a ---- atom can cause the metadata parser to stop advancing through the input. The custom-field atom traversal repeatedly processes the malformed location, causing an infinite loop and denying service to a program that reads the crafted file. This issue is fixed in version 2.3.0.

Affected products

tinytag: from 2.0.0, < 2.3.0

References

https://github.com/tinytag/tinytag/commit/9ada221ba44990cb02cd9002d992186e037b515e
https://github.com/tinytag/tinytag/pull/326
https://github.com/tinytag/tinytag/releases/tag/2.3.0
https://github.com/tinytag/tinytag/security/advisories/GHSA-24cc-9352-h2pg

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