# bootstrap Cross-site Scripting vulnerability

Advisory record · `GHSA-ph58-4vrj-w6hr`

- **Identifiers:** `GHSA-ph58-4vrj-w6hr` · `CVE-2018-20677` · `PKSA-p8c4-fdq4-sycz`
- **State:** Confirmed
- **Severity:** CVSS 6.1 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-79](https://cwe.mitre.org/data/definitions/79.html)
- **Tags:** [Cross-site scripting (XSS)](https://agentprime.io/advisories/tag/xss.md)
- **Published:** 17 Jan 2019
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 17 Jan 2019, 13:57 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `bootstrap` (npm): affected `<3.4.0`; fixed in `3.4.0`
- `bootstrap-sass` (npm): affected `<3.4.0`; fixed in `3.4.0`
- `twbs/bootstrap` (Packagist): affected `<3.4.0`; fixed in `3.4.0`
- `org.webjars:bootstrap` (Maven): affected `<3.4.0`; fixed in `3.4.0`
- `bootstrap` (RubyGems): affected `<3.4.0`; fixed in `3.4.0`
- `bootstrap-sass` (RubyGems): affected `<3.4.0`; fixed in `3.4.0`
- `bootstrap` (NuGet): affected `<3.4.0`; fixed in `3.4.0`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 6.1 Medium, CVSS 3.0: `CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`, from GitHub Advisory Database

- **CISA KEV:** Not listed.
- **EPSS:** 0.040, the 90th percentile, on 10 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the GitHub Advisory Database, published 17 Jan 2019. New records show when each source confirmed them.

## Sources

- [GitHub Advisory Database: GHSA-ph58-4vrj-w6hr](https://github.com/advisories/GHSA-ph58-4vrj-w6hr)
- [OSV: GHSA-ph58-4vrj-w6hr](https://osv.dev/vulnerability/GHSA-ph58-4vrj-w6hr)
- <https://nvd.nist.gov/vuln/detail/CVE-2018-20677>
- <https://github.com/twbs/bootstrap/issues/27915#issuecomment-452196628>
- <https://github.com/twbs/bootstrap/issues/27915#issuecomment-452140906>
- <https://github.com/twbs/bootstrap/issues/27045>
- <https://github.com/twbs/bootstrap/pull/27047>
- <https://github.com/twbs/bootstrap/commit/2a5ba23ce8f041f3548317acc992ed8a736b609d>
- <https://lists.apache.org/thread.html/rd0e44e8ef71eeaaa3cf3d1b8b41eb25894372e2995ec908ce7624d26@%3Ccommits.pulsar.apache.org%3E>
- <https://lists.apache.org/thread.html/52e0e6b5df827ee7f1e68f7cc3babe61af3b2160f5d74a85469b7b0e@%3Cdev.superset.apache.org%3E>
- <https://github.com/twbs/bootstrap>
- <https://github.com/rubysec/ruby-advisory-db/blob/master/gems/bootstrap/CVE-2018-20677.yml>
- <https://github.com/rubysec/ruby-advisory-db/blob/master/gems/bootstrap-sass/CVE-2018-20677.yml>
- <https://blog.getbootstrap.com/2018/12/13/bootstrap-3-4-0>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-ph58-4vrj-w6hr>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-ph58-4vrj-w6hr/>. Everything for agents: <https://agentprime.io/llms.txt>.