Regular Expression Denial of Service (ReDOS)

Exploitation

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

CVSS

5.3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS

• CVE-2021-29060: 3.13% estimated exploitation activity in the next 30 days; percentile 87.90 (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.

In the npm package color-string, there is a ReDos (Regular Expression Denial of Service) vulnerability regarding an exponential time complexity for linearly increasing input lengths for hwb() color strings. Strings reaching more than 5000 characters would see several milliseconds of processing time; strings reaching more than 50,000 characters began seeing 1500ms (1.5s) of processing time. The cause was due to a the regular expression that parses hwb() strings - specifically, the hue value - where the integer portion of the hue value used a 0-or-more quantifier shortly thereafter followed by a 1-or-more quantifier. This caused excessive backtracking and a cartesian scan, resulting in exponential time complexity given a linear increase in input length.

Published by the source

22 Jun 2021, 01:14 UTC

Last modified by the source

8 Nov 2023, 04:05 UTC

Source last checked

26 Oct 2026, 12:20 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-257v-vj4p-3w2h

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-257v-vj4p-3w2h

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# Patch Next advisory brief: CVE-2021-29060

Advisory: Regular Expression Denial of Service (ReDOS)
IDs: CVE-2021-29060, GHSA-257v-vj4p-3w2h
Record: https://patchnext.com/advisories/cve-2021-29060 (revision 2, source checked 26 Oct 2026, 12:20 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: color-string 1.5.5. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm color-string: affected < 1.5.5; fixed in 1.5.5

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

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on color-string.
- 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-257v-vj4p-3w2h (OSV record GHSA-257v-vj4p-3w2h lists affected ranges: npm color-string >=0 <1.5.5 (fixed))
- Verified: https://github.com/advisories/GHSA-257v-vj4p-3w2h (GitHub-reviewed advisory GHSA-257v-vj4p-3w2h lists affected ranges: npm color-string >=0 <1.5.5)

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