Resource exhaustion in Pygments
CVE-2026-4539
A security flaw has been discovered in pygments up to 2.19.2. The impacted element is the function AdlLexer of the file pygments/lexers/archetype.py. The manipulation results in inefficient regular expression complexity. The attack is only possible with local access. The exploit has been released to the public and may be used for attacks. The project was informed of the problem early through an issue report but has not responded yet.
Vulnerability class: DoS (Denial of Service)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.3 (Low). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.002 (4.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 4th percentile — 4.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000
Affected products
- Pygments — versions 2.19.0, 2.19.1, 2.19.2
Weakness classification (CWE)
References
- vuldb.com/ (technical-description, vdb-entry)
- vuldb.com/ (signature, permissions-required)
- vuldb.com/ (third-party-advisory)
- github.com/pygments/pygments/issues/3058 (issue-tracking, exploit)
- github.com/pygments/pygments/ (product)
Frequently asked questions
- What is CVE-2026-4539?
- CVE-2026-4539 is a low-severity vulnerability in Pygments, classified under Uncontrolled Resource Consumption. CVSS score: 3.3/10. Published 2026-03-22.
- How severe is CVE-2026-4539?
- Low severity. CVSS v3 base score is 3.3 out of 10.