# HTTP response splitting in CGI

Advisory record · `GHSA-vc47-6rqg-c7f5`

- **Identifiers:** `GHSA-vc47-6rqg-c7f5` · `BIT-ruby-2021-33621` · `BIT-ruby-min-2021-33621` · `CVE-2021-33621`
- **State:** Confirmed
- **Severity:** CVSS 8.8 High
- **Critical:** No
- **Weakness (CWE):** [CWE-74](https://cwe.mitre.org/data/definitions/74.html) · [CWE-436](https://cwe.mitre.org/data/definitions/436.html)
- **Tags:** [Other injection](https://agentprime.io/advisories/tag/injection.md) · [CWE-436](https://agentprime.io/advisories/tag/cwe-436.md)
- **Published:** 19 Nov 2022
- **Updated:** 13 Aug 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 19 Nov 2022, 00:30 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `cgi` (RubyGems): affected `>=0.3.0, <0.3.5 || >=0.2.0, <0.2.2 || <0.1.0.2`; fixed in `0.3.5`, `0.2.2`, `0.1.0.2`

## 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

- 8.8 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`, from GitHub Advisory Database

- **CISA KEV:** Not listed.
- **EPSS:** 0.025, the 84th percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 15:16 UTC: First seen by agentprime
- 31 Oct 2026, 15:16 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-vc47-6rqg-c7f5)

## Sources

- [GitHub Advisory Database: GHSA-vc47-6rqg-c7f5](https://github.com/advisories/GHSA-vc47-6rqg-c7f5)
- [OSV: GHSA-vc47-6rqg-c7f5](https://osv.dev/vulnerability/GHSA-vc47-6rqg-c7f5)
- <https://nvd.nist.gov/vuln/detail/CVE-2021-33621>
- <https://hackerone.com/reports/1204695>
- <https://github.com/rubysec/ruby-advisory-db/blob/master/gems/cgi/CVE-2021-33621.yml>
- <https://lists.debian.org/debian-lts-announce/2023/06/msg00012.html>
- <https://lists.debian.org/debian-lts-announce/2024/09/msg00000.html>
- <https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/DQR7LWED6VAPD5ATYOBZIGJQPCUBRJBX>
- <https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/THVTYHHEOVLQFCFHWURZYO7PVUPBHRZD>
- <https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/YACE6ORF2QBXXBK2V2CM36D7TZMEJVAS>
- <https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/DQR7LWED6VAPD5ATYOBZIGJQPCUBRJBX>
- <https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/THVTYHHEOVLQFCFHWURZYO7PVUPBHRZD>
- <https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/YACE6ORF2QBXXBK2V2CM36D7TZMEJVAS>
- <https://security.gentoo.org/glsa/202401-27>

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-vc47-6rqg-c7f5>, 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-vc47-6rqg-c7f5/>. Everything for agents: <https://agentprime.io/llms.txt>.