# Skipper has OPA body-authz bypass: truncated_body mitigation fails open on chunked/HTTP-2 (incomplete fix GHSA-8qqm-fp2q-v734)

Advisory record · `GHSA-5gpm-rgj3-9q76`

- **Identifiers:** `GHSA-5gpm-rgj3-9q76` · `CVE-2026-86043` · `GO-2026-6495`
- **State:** Confirmed
- **Severity:** CVSS 7.5 High
- **Critical:** No
- **Weakness (CWE):** [CWE-863](https://cwe.mitre.org/data/definitions/863.html)
- **Tags:** [Broken access control](https://agentprime.io/advisories/tag/access-control.md)
- **Published:** 17 Sept 2026
- **Updated:** 28 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 17 Sept 2026, 17:05 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `github.com/zalando/skipper` (Go): affected `<0.27.37`; fixed in `0.27.37`

## Machine-written summary

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

> Skipper versions before 0.27.37 can let oversized request bodies bypass Open Policy Agent authorization when the policy uses the \`truncated_body\` mitigation from GHSA-8qqm-fp2q-v734. A remote, unauthenticated attacker can send a chunked or HTTP/2 request without a Content-Length header, so the flag stays false and the full body reaches the upstream. Upgrade to Skipper 0.27.37, which is listed as the fixed version.

Written 1 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

- 7.5 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0045, the 39th percentile, on 9 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## 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-5gpm-rgj3-9q76)

## Sources

- [GitHub Advisory Database: GHSA-5gpm-rgj3-9q76](https://github.com/advisories/GHSA-5gpm-rgj3-9q76)
- [OSV: GHSA-5gpm-rgj3-9q76](https://osv.dev/vulnerability/GHSA-5gpm-rgj3-9q76)
- <https://github.com/zalando/skipper/security/advisories/GHSA-5gpm-rgj3-9q76>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-86043>
- <https://github.com/zalando/skipper/commit/2cfceabaa6ff0af65b312dcb9bcbe84691b9d507>
- <https://github.com/zalando/skipper>
- <https://github.com/zalando/skipper/releases/tag/v0.27.35>
- <https://github.com/zalando/skipper/releases/tag/v0.27.37>
- <https://github.com/zalando/skipper/tree/v0.27.35>

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-5gpm-rgj3-9q76>, 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-5gpm-rgj3-9q76/>. Everything for agents: <https://agentprime.io/llms.txt>.