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Vulnerability · Published Jun 22, 2025 · Assigned by VulDB

CVE-2025-6493CodeMirror Markdown Mode markdown.js redos

Medium 5.3

In plain English

A medium-severity regular-expression denial of service in CodeMirror. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 45% of all known vulnerabilities).

Severity (CVSS 3.1)5.3Medium
Exploit odds (30 days)0.5%top 54.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

A weakness has been identified in CodeMirror up to 5.65.20. Affected is an unknown function of the file mode/markdown/markdown.js of the component Markdown Mode. This manipulation causes inefficient regular expression complexity. It is possible to initiate the attack remotely. The exploit has been made available to the public and could be exploited. Upgrading to version 6.0 is able to address this issue. You should upgrade the affected component. Not all code samples mentioned in the GitHub issue can be found. The repository mentions, that "CodeMirror 6 exists, and is [...] much more actively maintained."

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12codemirror-jsno fix listedDEBIAN-CVE-2025-6493
Debian:13codemirror-jsno fix listedDEBIAN-CVE-2025-6493
Debian:14codemirror-jsno fix listedDEBIAN-CVE-2025-6493
Ubuntu:22.04:LTScodemirror-jsno fix listedUBUNTU-CVE-2025-6493
Ubuntu:24.04:LTScodemirror-jsno fix listedUBUNTU-CVE-2025-6493
Ubuntu:25.10codemirror-jsno fix listedUBUNTU-CVE-2025-6493
Ubuntu:26.04:LTScodemirror-jsno fix listedUBUNTU-CVE-2025-6493
Ubuntu:26.10codemirror-jsno fix listedUBUNTU-CVE-2025-6493

Affected products (as reported)

VendorProductVersions
n/a CodeMirror 5.65.05.65.15.65.25.65.35.65.45.65.55.65.65.65.7

Weakness: CWE-1333, CWE-400 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C

References