Vulnerabilities
Misconfiguration
Compliance
CVE Vulnerabilities

CVE-2021-26813

Inefficient Regular Expression Complexity

Published: Mar 03, 2021 | Modified: Nov 21, 2024
CVSS 3.x
7.5
HIGH
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.x
5 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P
RedHat/V2
RedHat/V3
Ubuntu
MEDIUM
Vulnerability-free packages from our partners
root.io logo minimus.io logo echo.ai logo
Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2021-26813
CWEhttps://cwe.mitre.org/data/definitions/1333.html

markdown2 >=1.0.1.18, fixed in 2.4.0, is affected by a regular expression denial of service vulnerability. If an attacker provides a malicious string, it can make markdown2 processing difficult or delayed for an extended period of time.

Weakness

The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles.

Affected Software

NameVendorStart VersionEnd Version
Markdown2Markdown2_project1.0.1.18 (including)2.4.0 (excluding)
Python-markdown2Ubuntufocal*
Python-markdown2Ubuntugroovy*
Python-markdown2Ubuntuhirsute*
Python-markdown2Ubuntuimpish*
Python-markdown2Ubuntukinetic*
Python-markdown2Ubuntulunar*
Python-markdown2Ubuntumantic*
Python-markdown2Ubuntuoracular*
Python-markdown2Ubuntuplucky*
Python-markdown2Ubuntutrusty*

Extended Description

	  Attackers can create crafted inputs that
	  intentionally cause the regular expression to use
	  excessive backtracking in a way that causes the CPU
	  consumption to spike.

Potential Mitigations

References

Aqua Security is the largest pure-play cloud native security company, providing customers the freedom to innovate and run their businesses with minimal friction. The Aqua Cloud Native Security Platform provides prevention, detection, and response automation across the entire application lifecycle to secure the build, secure cloud infrastructure and secure running workloads wherever they are deployed.
Copyright © 2026 Aqua Security Software Ltd.   Privacy Policy | Terms of Use