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CVE-2025-6493

CodeMirror Markdown Mode markdown.js redos

6.9 Medium

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."

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
Low

Exploit likelihood

0.53%Up 0.5 points since Jun 23, 2025
90%50%10%1%

What each source reports

CVE List Score used 6.9

CodeMirror Markdown Mode markdown.js redos

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."

Record
CVE-2025-6493
CVSS 4.0
6.9 MediumCVSS: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 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
CVSS 3.0
5.3 MediumCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
CVSS 2.0
5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P/E:POC/RL:OF/RC:C
Weakness
CWE-1333, CWE-400
Updated
2026-11-02
EUVDEUVD-2025-28740 6.9

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."

Record
EUVD-2025-28740
CVSS 4.0
6.9 MediumCVSS: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
Updated
2026-11-02
GitHub AdvisoriesGHSA-pff4-9qxc-79mq 5.5

A vulnerability was found in CodeMirror up to 5.17.0 and classified as problematic. Affected by...

A vulnerability was found in CodeMirror up to 5.17.0 and classified as problematic. Affected by this issue is some unknown functionality of the file mode/markdown/markdown.js of the component Markdown Mode. The manipulation leads to inefficient regular expression complexity. The attack may be launched remotely. The exploit has been disclosed to the public and may be used. 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."

Record
GHSA-pff4-9qxc-79mq
CVSS 4.0
5.5 MediumCVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Weakness
CWE-400
Updated
2026-11-02
NVD 5.5

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."

Record
CVE-2025-6493
CVSS 4.0
5.5 MediumCVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness
CWE-400, CWE-1333
Updated
2026-11-02
OSV 5.5

CodeMirror Markdown Mode markdown.js redos

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."

Record
CVE-2025-6493
CVSS 4.0
5.5 MediumCVSS: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
Weakness
CWE-1333, CWE-400
Updated
2026-11-02
OSVDEBIAN-CVE-2025-6493 5.5

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."

Record
DEBIAN-CVE-2025-6493
CVSS 4.0
5.5 MediumCVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-02
OSVUBUNTU-CVE-2025-6493 5.5

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."

Record
UBUNTU-CVE-2025-6493
CVSS 4.0
5.5 MediumCVSS: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 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Updated
2026-11-02

Affected packages

Affected packages
PackageAffectedFixed
codemirror-js
Debian:12
All versions, plus listed versions
5.65.0+~cs5.83.9-25.65.0+~cs5.83.9-35.65.20+~cs5.83.25-1
None known
codemirror-js
Debian:13
All versions, plus listed versions
5.65.0+~cs5.83.9-35.65.20+~cs5.83.25-1
None known
codemirror-js
Debian:14
All versions, plus listed versions
5.65.0+~cs5.83.9-35.65.20+~cs5.83.25-1
None known
codemirror-js
Ubuntu:16.04:LTS
All versions, plus listed versions
5.4.0-1
None known
codemirror-js
Ubuntu:18.04:LTS
All versions, plus listed versions
5.4.0-15.19.0-1
None known
codemirror-js
Ubuntu:20.04:LTS
All versions, plus listed versions
5.43.0-15.49.2-15.50.2-15.51.0-1
None known
codemirror-js
Ubuntu:22.04:LTS
All versions, plus listed versions
5.59.2+~cs0.23.109-15.62.2+~cs5.83.6-15.63.3+~cs5.83.9-15.65.0+~cs5.83.9-1
None known
codemirror-js
Ubuntu:24.04:LTS
All versions, plus listed versions
5.65.0+~cs5.83.9-3
None known
codemirror-js
Ubuntu:25.10
All versions, plus listed versions
5.65.0+~cs5.83.9-3
None known
codemirror-js
Ubuntu:26.10
All versions, plus listed versions
5.65.20+~cs5.83.25-1
None known
codemirror-js
Ubuntu:26.04:LTS
All versions, plus listed versions
5.65.0+~cs5.83.9-35.65.20+~cs5.83.25-1
None known

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2025-6493 is a medium vulnerability (CVSS 6.9) in codemirror-js, published June 22, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.53%, the 45th percentile. No source names a fixed version.

References

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