# Improper Restriction of Rendered UI Layers or Frames in yourls

Advisory record · `GHSA-r6g8-jmj9-g945`

- **Identifiers:** `GHSA-r6g8-jmj9-g945` · `CVE-2021-3734` · `PKSA-ds9p-gn9y-hv4j`
- **State:** Confirmed
- **Severity:** CVSS 6.5 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-352](https://cwe.mitre.org/data/definitions/352.html) · [CWE-1021](https://cwe.mitre.org/data/definitions/1021.html)
- **Tags:** [Cross-site request forgery (CSRF)](https://agentprime.io/advisories/tag/csrf.md) · [CWE-1021](https://agentprime.io/advisories/tag/cwe-1021.md)
- **Published:** 30 Aug 2021
- **Updated:** 8 Nov 2023
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 30 Aug 2021, 16:22 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `yourls/yourls` (Packagist): affected `<=1.8.1`; no fixed version yet

## Machine-written summary

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

> The yourls/yourls package, versions 1.8.1 and earlier, is affected by an improper restriction of rendered UI layers or frames, which is a clickjacking-type weakness. The source gives few details on how an attacker would trigger it or what exact impact follows from it. No fixed version is listed.

Written 5 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

- 6.5 Medium, CVSS 3.0: `CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N`, from CNA (@huntrdev)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0040, the 34th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:33 UTC: First seen by agentprime
- 31 Oct 2026, 14:33 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-r6g8-jmj9-g945)

## Sources

- [GitHub Advisory Database: GHSA-r6g8-jmj9-g945](https://github.com/advisories/GHSA-r6g8-jmj9-g945)
- [OSV: GHSA-r6g8-jmj9-g945](https://osv.dev/vulnerability/GHSA-r6g8-jmj9-g945)
- <https://nvd.nist.gov/vuln/detail/CVE-2021-3734>
- <https://github.com/yourls/yourls/commit/0a70acdcfb5fcbc63dbc5750018d608288eba3fe>
- <https://github.com/yourls/yourls>
- <https://huntr.dev/bounties/dd2e2dbe-efe5-49ec-be11-7a7e7c41debd>

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-r6g8-jmj9-g945>, 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-r6g8-jmj9-g945/>. Everything for agents: <https://agentprime.io/llms.txt>.