fonttools XML External Entity Injection (XXE) Vulnerability
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-611 and the CVSS impact.
Summary
fontTools is a library for manipulating fonts, written in Python. The subsetting module has a XML External Entity Injection (XXE) vulnerability which allows an attacker to resolve arbitrary entities when a candidate font (OT-SVG fonts), which contains a SVG table, is parsed. This allows attackers to include arbitrary files from the filesystem fontTools is running on or make web requests from the host system. This vulnerability has been patched in version 4.43.0.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| fonttools | fonttools | 4.28.2 to before 4.43.0 | 4.43.0 | Patch available | CNA |
| — | fonttools (PyPI) | 4.28.2 to before 4.43.0 | 4.43.0 | Patch available | GHSA-6673-4983-2vx5 |
- fonttools Vendorfonttools Affected 4.28.2 to before 4.43.0 Fixed in 4.43.0 Patch available CNA
- fonttools (PyPI) Vendor— Affected 4.28.2 to before 4.43.0 Fixed in 4.43.0 Patch available GHSA-6673-4983-2vx5
Remediation
- Fix · CNA fonttools (fonttools) Fixed in 4.43.0
- Fix · GHSA-6673-4983-2vx5 fonttools (PyPI) Fixed in 4.43.0 Advisory →
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
Not affected: 3 products
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2023-45139
- 2026-10-03 Alias added: GHSA-6673-4983-2vx5
References
Other 6
- https://github.com/fonttools/fonttools/releases/tag/4.43.0
- https://lists.fedoraproject.org/archives/list/[email protected]/message/VY63B4SGY4QOQGUXMECRGD6K3YT3GJ75/
- http://www.openwall.com/lists/oss-security/2024/03/09/1
- http://www.openwall.com/lists/oss-security/2024/03/08/2
- https://github.com/fonttools/fonttools
- https://lists.fedoraproject.org/archives/list/[email protected]/message/VY63B4SGY4QOQGUXMECRGD6K3YT3GJ75
More Fonttools vulnerabilities
- TI-2025-40560 fontTools is Vulnerable to Arbitrary File Write and XML injection in fontTools.varLib CVSS 3.1CRITICAL 9.8
Sources
- CVE-2023-45139 · CVE Program
- CVE-2023-45139 · NVD
- FIRST EPSS
- GHSA-6673-4983-2vx5 · GitHub Advisory Database · CC BY 4.0
- CVE-2023-45139 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences