# cbor2 (PyPI) vulnerabilities

4 known vulnerabilities (3 high, 1 medium), with the versions each affects and the releases that fix them.

## At a glance

- Latest release: 6.2.1 (Nov 7, 2026): no advisory affects it
- Newest unaffected release: 6.2.1 (Nov 7, 2026), the latest release
- Weekly downloads: 17.3M
- Releases: 54 since 1.0.0 (Jun 8, 2016)
- Registry: https://pypi.org/project/cbor2/
- Releases read: Nov 8, 2026

## Version timeline

Affected versions per advisory, in version order:

- CVE-2026-26209: 1.0.0 to 5.8.0 (5.9.0 is outside it)
- CVE-2025-68131: 3.0.0 to 5.7.1 (5.8.0 is outside it)
- CVE-2025-64076: 1.0.0 to 5.7.0 (5.7.1 is outside it)
- CVE-2024-26134: 1.0.0 to 5.2.0 (5.2.0.post1 is outside it); 5.3.0 to 5.6.1 (5.6.2 is outside it)

## Advisories (4)

### [CVE-2026-26209](https://cve.now/CVE-2026-26209): cbor2 has a Denial of Service via Uncontrolled Recursion in cbor2.loads

- Severity: High 7.5
- Published: Mar 23, 2026
- Affected: fixed in 5.9.0.
- Fixed in 5.9.0 (released Mar 22, 2026, 1 day before disclosure).
- The latest release, 6.2.1, is not affected.

### [CVE-2025-68131](https://cve.now/CVE-2025-68131): CBORDecoder reuse can leak shareable values across decode calls

- Severity: Medium 5.5
- Published: Dec 31, 2025
- Affected: from 3.0.0, fixed in 5.8.0.
- Fixed in 5.8.0 (released Dec 30, 2025, 1 day before disclosure).
- The latest release, 6.2.1, is not affected.

### [CVE-2025-64076](https://cve.now/CVE-2025-64076): Multiple vulnerabilities exist in cbor2 through version 5.7.0 in the decode\_definite\_long\_string() function of the C extension decoder…

- Severity: High 7.5
- Published: Nov 18, 2025
- Affected: fixed in 5.7.1.
- Fixed in 5.7.1 (released Oct 24, 2025, 25 days before disclosure).
- The latest release, 6.2.1, is not affected.

### [CVE-2024-26134](https://cve.now/CVE-2024-26134): CBOR2 decoder has potential buffer overflow

- Severity: High 7.5
- Published: Feb 19, 2024
- Affected: from 5.5.1, fixed in 5.6.2; from 5.5.1, fixed in 5.6.2.
- Fixed in 5.6.2 (released Feb 19, 2024, the day of disclosure).
- The latest release, 6.2.1, is not affected.

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