CVE-2025-6493Public exploitNetwork attack vector

Application hang via Markdown regex backtracking

Published Jun 22, 2025 · Updated Sep 29, 2025

Regular-expression denial of service in CodeMirror 5.65.0 through 5.65.20 allows remote attackers to freeze embedding applications. The Markdown tokenizer in mode/markdown/markdown.js applies several unbounded, backtracking-prone regular expressions to crafted input lacking expected terminators. Any browser or server-side application that passes attacker-controlled Markdown to this mode can suffer sustained CPU consumption and an application hang.

CVSS severityUnavailable
Unscored
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Regular-expression denial of service in CodeMirror 5.65.0 through 5.65.20 allows remote attackers to freeze embedding applications. The Markdown tokenizer in mode/markdown/markdown.js applies several unbounded, backtracking-prone regular expressions to crafted input lacking expected terminators. Any browser or server-side application that passes attacker-controlled Markdown to this mode can suffer sustained CPU consumption and an application hang.

The record

CVE
CVE-2025-6493
Published
Jun 22, 2025
Updated
Sep 29, 2025
Vendor
CodeMirror
Product
CodeMirror
Classifications
CWE-1333, CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 22, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 29, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.65.0
  2. Affected versionversion=5.65.1
  3. Affected versionversion=5.65.10
  4. Affected versionversion=5.65.11
  5. Affected versionversion=5.65.12
  6. Affected versionversion=5.65.13
  7. Affected versionversion=5.65.14
  8. Affected versionversion=5.65.15
  9. Affected versionversion=5.65.16
  10. Affected versionversion=5.65.17
  11. Affected versionversion=5.65.18
  12. Affected versionversion=5.65.19
  13. Affected versionversion=5.65.2
  14. Affected versionversion=5.65.20
  15. Affected versionversion=5.65.3
  16. Affected versionversion=5.65.4
  17. Affected versionversion=5.65.5
  18. Affected versionversion=5.65.6
  19. Affected versionversion=5.65.7
  20. Affected versionversion=5.65.8
  21. Affected versionversion=5.65.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

CodeMirror · CodeMirrorversion=5.65.0; version=5.65.1; version=5.65.10; version=5.65.11; version=5.65.12; version=5.65.13; version=5.65.14; version=5.65.15; version=5.65.16; version=5.65.17; version=5.65.18; version=5.65.19; version=5.65.2; version=5.65.20; version=5.65.3; version=5.65.4; version=5.65.5; version=5.65.6; version=5.65.7; version=5.65.8; version=5.65.9

Published CVSS scores

5.3VulDBCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
5.3VulDBCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
5.0VulDBAV:N/AC:L/Au:N/C:N/I:N/A:P/E:POC/RL:OF/RC:C
6.9VulDBCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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