How severe is CVE-2026-4539?

CVE-2026-4539 has a CVSS 3.x base score of 3.3, rated low severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2026-4539 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-4539?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-4539 have an EU (EUVD) identifier?

Yes. CVE-2026-4539 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-14287.

When was CVE-2026-4539 published?

CVE-2026-4539 was published on 2026-03-22 and last updated on 2026-06-17.

CVE-2026-4539

CVE-2026-4539 is a low-severity vulnerability with a CVSS 3.x base score of 3.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

Severity: Low (CVSS 3.x base score 3.3)
CVSS v2: 1.7
CVSS v4: 1.9
EPSS exploit prediction: 0% (5th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-14287
Weakness: CWE-400
Published: 2026-03-22
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-4539?: CVE-2026-4539 has a CVSS 3.x base score of 3.3, rated low severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2026-4539 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (5th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-4539?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-4539 have an EU (EUVD) identifier?: Yes. CVE-2026-4539 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-14287.
When was CVE-2026-4539 published?: CVE-2026-4539 was published on 2026-03-22 and last updated on 2026-06-17.

References

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