CVE-2021-27291

Pygments vulnerability

CVSS

7.5

EPSS

3.9%

EPSS pct

89th

Exploited

No known

In pygments 1.1+, fixed in 2.7.4, the lexers used to parse programming languages rely heavily on regular expressions. Some of the regular expressions have exponential or cubic worst-case complexity and are vulnerable to ReDoS. By crafting malicious input, an attacker can cause a denial of service.

Affected vendor

Pygments

Affected product

Pygments

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weakness type (CWE)

CWE-1333 — Inefficient Regular Expression Complexity

Published

2021-03-17

Risk analysis

Based on its CVSS vector, this vulnerability is exploitable over the network, low attack complexity, requiring no privileges, no user interaction. Successful exploitation leads to high impact to availability.

Its EPSS score of 3.9% reflects a lower probability of exploitation activity in the wild over the next 30 days, placing it above 89% of all scored CVEs.

Check your external exposure to CVE-2021-27291

Confirm whether Pygments Pygments is running on any internet-facing host or subdomain.
Match discovered service fingerprints against the version affected by CVE-2021-27291.
Prioritise remediation if the asset is public, business-critical, or near authentication/payment flows.

How ThreatPort helps with CVE-2021-27291

ThreatPort's external attack surface scanner checks your internet-facing assets — agentlessly, from the outside in — for the exposed services and versions that CVE-2021-27291 affects, then prioritises the finding by real risk using CISA KEV and FIRST.org EPSS.

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