Regular Expression Denial of Service in ansi2html

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

not scored

EPSS

• CVE-2015-9239: 1.13% estimated exploitation activity in the next 30 days; percentile 66.50 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

The ansi2html package is affected by a regular expression denial of service vulnerability when certain types of user input is passed in. Proof of concept Results of the above Recommendation At the time of this writing, February 2018, all versions of ansi2html remain vulnerable, and the package has not been updated for 4 years. In order to use this package safely, it is necessary to avoid passing user input to the package, or to limit the size of the input string to a size with a parse time you find acceptable. Unfortunately, the match time grows at quite a small character count, so it is unlikely for it to both allow strings of a useful size while protecting against the denial of service attack. In the case that user input of significant length must be parsed by ansi2html, the best mitigation is to use an alternative module that is actively maintained and provides similar functionality. There are [multiple modules fitting this criteria available on npm.]available on npm

Published by the source

1 Sep 2020, 15:17 UTC

Last modified by the source

8 Nov 2023, 03:58 UTC

Source last checked

26 Oct 2026, 12:08 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-c2v2-7rcg-2ch7

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-c2v2-7rcg-2ch7

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# Patch Next advisory brief: CVE-2015-9239

Advisory: Regular Expression Denial of Service in ansi2html
IDs: CVE-2015-9239, GHSA-c2v2-7rcg-2ch7
Record: https://patchnext.com/advisories/cve-2015-9239 (revision 2, source checked 26 Oct 2026, 12:08 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm ansi2html: affected every version

## Suggested inspection (read-only)
- `npm ls ansi2html --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on ansi2html.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-c2v2-7rcg-2ch7 (OSV record GHSA-c2v2-7rcg-2ch7 lists affected ranges: npm ansi2html >=0.0.0)
- Verified: https://github.com/advisories/GHSA-c2v2-7rcg-2ch7 (GitHub-reviewed advisory GHSA-c2v2-7rcg-2ch7 lists affected ranges: npm ansi2html >=0.0.0)

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