# agent-router: MCP session resume does not verify the embedded anti-hijacking subject; default Helm seed makes session IDs forgeable

Advisory record · `GHSA-953h-535j-jg2v`

- **Identifiers:** `GHSA-953h-535j-jg2v`
- **State:** Confirmed
- **Severity:** CVSS 4.0, no score published
- **Critical:** No
- **Weakness (CWE):** [CWE-798](https://cwe.mitre.org/data/definitions/798.html) · [CWE-863](https://cwe.mitre.org/data/definitions/863.html)
- **Tags:** [Hard-coded credentials](https://agentprime.io/advisories/tag/hard-coded-credentials.md) · [Broken access control](https://agentprime.io/advisories/tag/access-control.md)
- **Published:** 19 Oct 2026
- **Updated:** 19 Oct 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 19 Oct 2026, 16:53 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `github.com/envoyproxy/ai-gateway` (Go): affected `>=0.4.0-rc1, <1.2.0-rc1`; fixed in `1.2.0-rc1`

## 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

- Score not published, CVSS 4.0: `CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`, from GitHub Advisory Database

- **CISA KEV:** Not listed.
- **EPSS:** No score.

## Timeline

- 31 Oct 2026, 14:12 UTC: First seen by agentprime
- 31 Oct 2026, 14:12 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-953h-535j-jg2v)

## Sources

- [GitHub Advisory Database: GHSA-953h-535j-jg2v](https://github.com/advisories/GHSA-953h-535j-jg2v)
- [OSV: GHSA-953h-535j-jg2v](https://osv.dev/vulnerability/GHSA-953h-535j-jg2v)
- <https://github.com/theagentrouter/agent-router/security/advisories/GHSA-953h-535j-jg2v>
- <https://github.com/theagentrouter/agent-router/pull/2740>
- <https://github.com/theagentrouter/agent-router/pull/2755>
- <https://github.com/theagentrouter/agent-router/commit/0d1e73037076d72251342d0ea578a36ffb7002c7>
- <https://github.com/theagentrouter/agent-router/commit/994579660ae2a9f2feef3cb77766e155746858b4>
- <https://github.com/theagentrouter/agent-router>

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-953h-535j-jg2v>, 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-953h-535j-jg2v/>. Everything for agents: <https://agentprime.io/llms.txt>.