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Vulnerability · Published Jul 1, 2020 · Assigned by GitHub_M

CVE-2020-5238Denial of service in table parsing in cmark-gfm

Medium 6.5

In plain English

A medium-severity improper input validation in cmark-gfm from github. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.6% (higher than 75% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)1.6%top 24.6% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

The table extension in GitHub Flavored Markdown before version 0.29.0.gfm.1 takes O(n * n) time to parse certain inputs. An attacker could craft a markdown table which would take an unreasonably long time to process, causing a denial of service. This issue does not affect the upstream cmark project. The issue has been fixed in version 0.29.0.gfm.1.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:8pandoc2.0.6-5.el8ALSA-2021:1972
AlmaLinux:8pandoc-common2.0.6-5.el8ALSA-2021:1972
Debian:12cmark-gfm0.29.0.gfm.2-1DEBIAN-CVE-2020-5238
Debian:13cmark-gfm0.29.0.gfm.2-1DEBIAN-CVE-2020-5238
Debian:14cmark-gfm0.29.0.gfm.2-1DEBIAN-CVE-2020-5238
Debian:12haskell-cmark-gfm0.2.1+ds1-1DEBIAN-CVE-2020-5238
Debian:13haskell-cmark-gfm0.2.1+ds1-1DEBIAN-CVE-2020-5238
Debian:14haskell-cmark-gfm0.2.1+ds1-1DEBIAN-CVE-2020-5238
Debian:12python-cmarkgfm0.7.0-1DEBIAN-CVE-2020-5238
Debian:13python-cmarkgfm0.7.0-1DEBIAN-CVE-2020-5238
Debian:14python-cmarkgfm0.7.0-1DEBIAN-CVE-2020-5238
Debian:12r-cran-commonmark1.8.0-1DEBIAN-CVE-2020-5238
Debian:13r-cran-commonmark1.8.0-1DEBIAN-CVE-2020-5238
Debian:14r-cran-commonmark1.8.0-1DEBIAN-CVE-2020-5238
Debian:12ruby-commonmarker0.21.0-1DEBIAN-CVE-2020-5238
Debian:13ruby-commonmarker0.21.0-1DEBIAN-CVE-2020-5238
Debian:14ruby-commonmarker0.21.0-1DEBIAN-CVE-2020-5238
Ubuntu:22.04:LTShaskell-cmark-gfmno fix listedUBUNTU-CVE-2020-5238
Ubuntu:24.04:LTShaskell-cmark-gfmno fix listedUBUNTU-CVE-2020-5238
Ubuntu:25.10haskell-cmark-gfmno fix listedUBUNTU-CVE-2020-5238
Ubuntu:26.04:LTShaskell-cmark-gfmno fix listedUBUNTU-CVE-2020-5238
Ubuntu:26.10haskell-cmark-gfmno fix listedUBUNTU-CVE-2020-5238
Ubuntu:22.04:LTSpython-cmarkgfmno fix listedUBUNTU-CVE-2020-5238
Ubuntu:24.04:LTSpython-cmarkgfmno fix listedUBUNTU-CVE-2020-5238
Ubuntu:25.10python-cmarkgfmno fix listedUBUNTU-CVE-2020-5238
Ubuntu:26.04:LTSpython-cmarkgfmno fix listedUBUNTU-CVE-2020-5238
Ubuntu:26.10python-cmarkgfmno fix listedUBUNTU-CVE-2020-5238
Ubuntu:22.04:LTSr-cran-commonmarkno fix listedUBUNTU-CVE-2020-5238
Ubuntu:24.04:LTSr-cran-commonmarkno fix listedUBUNTU-CVE-2020-5238
Ubuntu:25.10r-cran-commonmarkno fix listedUBUNTU-CVE-2020-5238
Ubuntu:26.04:LTSr-cran-commonmarkno fix listedUBUNTU-CVE-2020-5238
Ubuntu:26.10r-cran-commonmarkno fix listedUBUNTU-CVE-2020-5238

Affected products (as reported)

VendorProductVersions
github cmark-gfm < 0.29.0.gfm.1

Weakness: CWE-20 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

References