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CVE-2026-4539

19
FAUCET Score

CVE-2026-4539 describes a low-severity vulnerability in pygments versions up to 2.19.2, specifically within the AdlLexer function, which can lead to inefficient regular expression complexity (ReDoS). Exploitation requires local access and user privileges, potentially causing a denial of service due to resource exhaustion. Although a public exploit has been released, there is no indication of active exploitation, and community discussion or media coverage regarding this flaw is currently absent.

Impacted Technologies

VendorProductVersion(s)CPE
N/APygments
2.19.0, 2.19.1, 2.19.2CNA affected

CVSS Data

CVSS version used by this source: 4.0

1.9LOW

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector
LOCAL
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
LOW
User Interaction
NONE
VS Confidentiality
NONE
VS Integrity
NONE
VS Availability
LOW
SS Confidentiality
NONE
SS Integrity
NONE
SS Availability
NONE
Exploit Maturity
PROOF_OF_CONCEPT
CvssVersion
4.0

Exploit Intelligence

EPSS Score
0.16%
Probability of exploitation in next 30 days
EPSS Percentile
5.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0016 is in the 36th percentile among its peer group of 1,511 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

pippatch availablevia ghsa
Product: PygmentsFixed in: 2.20.0

Vendor Advisories (1)

pipGHSA-5239-wwwm-4pmqlow

Pygments has Regular Expression Denial of Service (ReDoS) due to Inefficient Regex for GUID Matching

Mar 22, 2026

References

github.com / pygments/pygments
github.com / pygments/pygments/issues/3058
vuldb.com
vuldb.com
vuldb.com