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No exploitation reportedFix available

CVE-2021-26813

No exploitation reported by the sources we read.

  • Published2021-03-03
  • WeaknessCWE-1333

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2021-03-0316:15CVE publishedNVD

Versions per branch

NVD · OSV
Fedoraproject fedora
BranchAffectedFixed in
32.x= 32no fix published
33.x= 33no fix published
34.x= 34no fix published
Markdown2 project markdown2
BranchAffectedFixed in
2.4≥ 1.0.1.18, < 2.4.02.4.0

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • python-markdown2Ubuntu:26.10all versions · no fixed version listed
  • python-markdown2Ubuntu:26.04:LTSall versions · no fixed version listed
  • python-markdown2Ubuntu:25.10all versions · no fixed version listed
  • python-markdown2Ubuntu:24.04:LTSall versions · no fixed version listed
  • python-markdown2Ubuntu:22.04:LTSall versions · no fixed version listed
  • python-markdown2Ubuntu:20.04:LTSall versions · no fixed version listed
  • python-markdown2SUSE:Package Hub 15 SP2all versions · fixed in 2.4.0-bp152.2.4.1
  • python-markdown2openSUSE:Tumbleweedall versions · fixed in 2.4.0-2.4

6 more package ranges on OSV.dev

Vendor advisories

  • CVE-2021-26813 Red Hat Product Security

    python-markdown2: Regular expression denial of service

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2021-03-03
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-jr9p-r423-9m2r

Frequently asked questions

What is CVE-2021-26813?

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.

Is CVE-2021-26813 actively exploited?

Active exploitation of CVE-2021-26813 has not been confirmed. Its EPSS score was 2.3% on 2026-11-08, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2021-26813?

CVE-2021-26813 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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Sources for this record