# Http4s: CookieJar middleware matches by substring, leaking cookies cross-origin

Advisory record · `GHSA-grh8-3p95-f9rr`

- **Identifiers:** `GHSA-grh8-3p95-f9rr` · `CVE-2026-69215`
- **State:** Confirmed
- **Severity:** CVSS 6.8 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-565](https://cwe.mitre.org/data/definitions/565.html) · [CWE-1275](https://cwe.mitre.org/data/definitions/1275.html)
- **Tags:** [CWE-565](https://agentprime.io/advisories/tag/cwe-565.md) · [CWE-1275](https://agentprime.io/advisories/tag/cwe-1275.md)
- **Published:** 15 Sept 2026
- **Updated:** 15 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 15 Sept 2026, 20:00 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `org.http4s:http4s-client_2.12` (Maven): affected `<0.23.35`; fixed in `0.23.35`
- `org.http4s:http4s-client_2.13` (Maven): affected `<0.23.35 || >=1.0.0-M1, <1.0.0-M47`; fixed in `0.23.35`, `1.0.0-M47`
- `org.http4s:http4s-client_3` (Maven): affected `<0.23.35 || >=1.0.0-M1, <1.0.0-M47`; fixed in `0.23.35`, `1.0.0-M47`

## 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

- 6.8 Medium, CVSS 3.1: `CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:N/A:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0050, the 43rd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:16 UTC: First seen by agentprime
- 31 Oct 2026, 14:16 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-grh8-3p95-f9rr)

## Sources

- [GitHub Advisory Database: GHSA-grh8-3p95-f9rr](https://github.com/advisories/GHSA-grh8-3p95-f9rr)
- [OSV: GHSA-grh8-3p95-f9rr](https://osv.dev/vulnerability/GHSA-grh8-3p95-f9rr)
- <https://github.com/http4s/http4s/security/advisories/GHSA-grh8-3p95-f9rr>
- <https://github.com/http4s/http4s/commit/c0a37f38d5ee2a568ba57bd9da62f8d79b8b1fcc>
- <https://github.com/http4s/http4s>
- <https://github.com/http4s/http4s/releases/tag/v0.23.35>
- <https://github.com/http4s/http4s/releases/tag/v1.0.0-M47>

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-grh8-3p95-f9rr>, 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-grh8-3p95-f9rr/>. Everything for agents: <https://agentprime.io/llms.txt>.