bootstrap Cross-site Scripting vulnerability

Exploitation

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

CVSS

6.1 · CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

EPSS

• CVE-2018-20677: 3.98% estimated exploitation activity in the next 30 days; percentile 90.51 (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 Bootstrap before 3.4.0, XSS is possible in the affix configuration target property.

Published by the source

17 Jan 2019, 13:57 UTC

Last modified by the source

10 Sep 2026, 03:47 UTC

Source last checked

26 Oct 2026, 12:31 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-ph58-4vrj-w6hr

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-ph58-4vrj-w6hr

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# Patch Next advisory brief: CVE-2018-20677

Advisory: bootstrap Cross-site Scripting vulnerability
IDs: CVE-2018-20677, GHSA-ph58-4vrj-w6hr
Record: https://patchnext.com/advisories/cve-2018-20677 (revision 2, source checked 26 Oct 2026, 12:31 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.webjars:bootstrap 3.4.0; bootstrap-sass 3.4.0; bootstrap 3.4.0; bootstrap-sass 3.4.0; bootstrap 3.4.0; twbs/bootstrap 3.4.0; bootstrap 3.4.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.webjars:bootstrap: affected < 3.4.0; fixed in 3.4.0
- RubyGems bootstrap-sass: affected < 3.4.0; fixed in 3.4.0
- npm bootstrap: affected < 3.4.0; fixed in 3.4.0
- npm bootstrap-sass: affected < 3.4.0; fixed in 3.4.0
- NuGet bootstrap: affected < 3.4.0; fixed in 3.4.0
- Packagist twbs/bootstrap: affected < 3.4.0; fixed in 3.4.0
- RubyGems bootstrap: affected < 3.4.0; fixed in 3.4.0

## Suggested inspection (read-only)
- Maven org.webjars:bootstrap: check the installed version with your package manager.
- RubyGems bootstrap-sass: check the installed version with your package manager.
- `npm ls bootstrap --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- `npm ls bootstrap-sass --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.
- NuGet bootstrap: check the installed version with your package manager.
- Packagist twbs/bootstrap: check the installed version with your package manager.
- RubyGems bootstrap: check the installed version with your package manager.

## 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 org.webjars:bootstrap, bootstrap-sass, bootstrap, twbs/bootstrap.
- 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-ph58-4vrj-w6hr (OSV record GHSA-ph58-4vrj-w6hr lists affected ranges: npm bootstrap >=0 =0 =0 =0 =0 =0 =0 <3.4.0 (fixed))
- Verified: https://github.com/advisories/GHSA-ph58-4vrj-w6hr (GitHub-reviewed advisory GHSA-ph58-4vrj-w6hr lists affected ranges: npm bootstrap >=0 =0 =0 =0 =0 =0 =0 <3.4.0)

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