# RubyGems Cross-site Scripting vulnerability

Advisory record · `GHSA-87qx-g5wg-mwmj`

- **Identifiers:** `GHSA-87qx-g5wg-mwmj` · `CVE-2018-1000078`
- **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:** 14 May 2022
- **Updated:** 13 Mar 2024
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 14 May 2022, 01:01 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `rubygems-update` (RubyGems): affected `<2.7.6`; fixed in `2.7.6`
- `org.jruby:jruby-stdlib` (Maven): affected `<9.1.16.0`; fixed in `9.1.16.0`

## Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

> Summary: The rubygems-update package before 2.7.6 is vulnerable to cross-site scripting through the homepage attribute shown by the gem server. An attacker can run script in a victim's browser if the victim visits a malicious gem hosted on a vulnerable gem server. Upgrade rubygems-update to 2.7.6 or later. The jruby-stdlib package is also listed with a fix in 9.1.16.0, but the source gives no further details about it.

Written 8 Nov 2026.

## 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:** 0.027, the 86th percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 15:13 UTC: First seen by agentprime
- 31 Oct 2026, 15:13 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-87qx-g5wg-mwmj)

## Sources

- [GitHub Advisory Database: GHSA-87qx-g5wg-mwmj](https://github.com/advisories/GHSA-87qx-g5wg-mwmj)
- [OSV: GHSA-87qx-g5wg-mwmj](https://osv.dev/vulnerability/GHSA-87qx-g5wg-mwmj)
- <https://nvd.nist.gov/vuln/detail/CVE-2018-1000078>
- <https://github.com/jruby/jruby/commit/0b06b48ab4432237ce5fc1bef47f2c6bcf7843f7>
- <https://github.com/rubygems/rubygems/commit/5971b486d4dbb2bad5d3445b3801c456eb0ce183>
- <https://github.com/rubygems/rubygems/commit/66a28b9275551384fdab45f3591a82d6b59952cb>
- <https://www.debian.org/security/2018/dsa-4259>
- <https://www.debian.org/security/2018/dsa-4219>
- <https://usn.ubuntu.com/3621-1>
- <https://lists.debian.org/debian-lts-announce/2019/05/msg00028.html>
- <https://lists.debian.org/debian-lts-announce/2018/07/msg00012.html>
- <https://lists.debian.org/debian-lts-announce/2018/04/msg00023.html>
- <https://lists.debian.org/debian-lts-announce/2018/04/msg00001.html>
- <https://lists.debian.org/debian-lts-announce/2018/04/msg00000.html>

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-87qx-g5wg-mwmj>, 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-87qx-g5wg-mwmj/>. Everything for agents: <https://agentprime.io/llms.txt>.