# HTTP/2 server crash due to HPACK encoder race in net/http

Advisory record · `GO-2026-6617`

- **Identifiers:** `GO-2026-6617` · `BIT-golang-2026-97032` · `CVE-2026-97032`
- **State:** Confirmed
- **Severity:** CVSS 7.5 High
- **Critical:** No
- **Weakness (CWE):** [CWE-362](https://cwe.mitre.org/data/definitions/362.html)
- **Tags:** [Race condition](https://agentprime.io/advisories/tag/race-condition.md)
- **Published:** 8 Oct 2026
- **Updated:** 16 Oct 2026
- **Reviewed by a person:** No

Published by OSV at 8 Oct 2026, 22:31 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `stdlib` (Go): affected `<1.26.9 || >=1.27.0-0, <1.27.2`; fixed in `1.26.9`, `1.27.2`
- `golang.org/x/net` (Go): affected `<0.60.0`; fixed in `0.60.0`

## Machine-written summary

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

> HTTP/2 servers in the Go standard library (versions before 1.26.9, and 1.27.0 up to but not including 1.27.2) and in golang.org/x/net (versions before 0.60.0) can crash. The HPACK encoder is modified from two goroutines without synchronization when a client changes the header table size while a response is being encoded. A remote client can exploit this by repeatedly sending requests while changing the header table size, causing the server to crash. Upgrade the Go standard library to 1.26.9 or 1.27.2, and golang.org/x/net to 0.60.0.

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:N/A:H`, from ADP (CISA-ADP)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0068, the 52nd percentile, on 7 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/GO-2026-6617)

## Sources

- [OSV: GO-2026-6617](https://osv.dev/vulnerability/GO-2026-6617)
- <https://go.dev/cl/847188>
- <https://go.dev/cl/847313>
- <https://groups.google.com/g/golang-announce/c/U2fTuyDJznI>
- <https://groups.google.com/g/golang-announce/c/ZPwCyRUuGBs>

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/GO-2026-6617>, 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/GO-2026-6617/>. Everything for agents: <https://agentprime.io/llms.txt>.