CVE-2025-6493
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."
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
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 Medium
CVSS: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 Medium
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 - CVSS 3.0
- 5.3 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - CVSS 2.0
- 5.0 Medium
AV: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Updated
- 2026-11-02
Affected packages
| Package | Affected | Fixed |
|---|---|---|
codemirror-jsDebian: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-jsDebian:13 |
All versions, plus listed versions 5.65.0+~cs5.83.9-35.65.20+~cs5.83.25-1 |
None known |
codemirror-jsDebian:14 |
All versions, plus listed versions 5.65.0+~cs5.83.9-35.65.20+~cs5.83.25-1 |
None known |
codemirror-jsUbuntu:16.04:LTS |
All versions, plus listed versions 5.4.0-1 |
None known |
codemirror-jsUbuntu:18.04:LTS |
All versions, plus listed versions 5.4.0-15.19.0-1 |
None known |
codemirror-jsUbuntu:20.04:LTS |
All versions, plus listed versions 5.43.0-15.49.2-15.50.2-15.51.0-1 |
None known |
codemirror-jsUbuntu: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-jsUbuntu:24.04:LTS |
All versions, plus listed versions 5.65.0+~cs5.83.9-3 |
None known |
codemirror-jsUbuntu:25.10 |
All versions, plus listed versions 5.65.0+~cs5.83.9-3 |
None known |
codemirror-jsUbuntu:26.10 |
All versions, plus listed versions 5.65.20+~cs5.83.25-1 |
None known |
codemirror-jsUbuntu:26.04:LTS |
All versions, plus listed versions 5.65.0+~cs5.83.9-35.65.20+~cs5.83.25-1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE 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.