CVE-2026-104266: tinytag Infinite Loop When Parsing Certain Vulnerability

MODERATE
Advisory Identifier: GHSA-24cc-9352-h2pg
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CVSS 6.5
CWE-835
Published
Advisory Summary

CVE-2026-104266 is a MODERATE (CVSS 6.5) infinite loop when parsing certain vulnerability (CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')) affecting tinytag libraries in the PyPI ecosystem. The issue involves infinite loop when parsing certain m4a files containing invalid atoms. Remediation is available by upgrading affected packages to version 2.3.0.

CVE-2026-104266 at a Glance

CVE Identifier CVE-2026-104266
GHSA Identifier GHSA-24cc-9352-h2pg
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop')
Affected Product tinytag
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-104266

To remediate this vulnerability, upgrade all affected tinytag dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

tinytag fixed: 2.3.0 
pip install tinytag>=2.3.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show tinytag

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-104266, inspect your installed packages using pip:

pip show tinytag

Analyze the terminal output to locate any version of tinytag in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.3.0), your application is affected.

Note: The pip show tinytag command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop'), where the product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop. In tinytag, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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.

CVE-2026-104266 Affected tinytag Versions

1 component(s)
Fixed Versions:
2.3.0
Product / Package Ecosystem Affected Versions Fixed Version
tinytag
pypi/tinytag
PyPI
≥ 2.0.0
< 2.3.0
2.3.0

References

GitHub Advisory / Wiki ADVISORY
https://github.com/tinytag/tinytag/security/advisories/GHSA-24cc-9352-h2pg
NVD — CVE-2026-104266 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-104266
tinytag Source Repository REPOSITORY
https://github.com/tinytag/tinytag/pull/326
Security Fix Commit FIX COMMIT
https://github.com/tinytag/tinytag/commit/9ada221ba44990cb02cd9002d992186e037b515e
tinytag Source Repository REPOSITORY
https://github.com/tinytag/tinytag
tinytag Release RELEASE
https://github.com/tinytag/tinytag/releases/tag/2.3.0

Frequently Asked Questions

What is CVE-2026-104266?
CVE-2026-104266 is a security vulnerability in tinytag involving Infinite loop when parsing certain M4A files containing invalid atoms under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop').
Which tinytag versions are affected?
Affected versions include releases prior to 2.3.0 across affected packages: tinytag.
What version fixes CVE-2026-104266?
Upgrading to 2.3.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is tinytag affected?
Yes, tinytag is affected in releases prior to 2.3.0. Upgrade your dependency to 2.3.0 or later.
What is the CVSS score of CVE-2026-104266?
CVE-2026-104266 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-104266?
CVE-2026-104266 is classified under CWE-835: Loop with Unreachable Exit Condition ('Infinite Loop') (The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.).
How can I check PyPI dependencies for CVE-2026-104266?
Run the dependency tree command: 'pip show tinytag'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-24cc-9352-h2pg",
  "modified" : "2026-10-15T20:16:47Z",
  "published" : "2026-10-15T20:16:47Z",
  "aliases" : [ "CVE-2026-104266" ],
  "summary" : "tinytag: Infinite loop when parsing certain M4A files containing invalid atoms",
  "details" : "### Impact\nAn 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.\n\n### Patches\nThe issue has been fixed in tinytag 2.3.0, by reusing the primary atom parsing code path that contains appropriate size checks.\n\n### Workarounds\nNo workarounds exist. Users must upgrade to tinytag 2.3.0.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "tinytag"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.0"
      }, {
        "fixed" : "2.3.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/tinytag/tinytag/security/advisories/GHSA-24cc-9352-h2pg"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-104266"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/tinytag/tinytag/pull/326"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/tinytag/tinytag/commit/9ada221ba44990cb02cd9002d992186e037b515e"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/tinytag/tinytag"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/tinytag/tinytag/releases/tag/2.3.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-835" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-10-15T20:16:47Z",
    "nvd_published_at" : "2026-10-15T18:17:22Z"
  }
}