---
id: "CVE-2026-111927"
kind: "vulnerability"
aliases: ["CVE-2026-111927"]
title: "Coder: hostname check lets prefix domains steal workspace API keys"
severity: "high"
cvss: 8.7
epss: null
exploited: false
status: "resolved"
category: "other"
products: [{"name": "coder", "fixed": ["2.35.4", "2.34.8", "2.33.12", "2.29.20"], "affected": ">= 2.35.0, < 2.35.4; >= 2.34.0, < 2.34.8; >= 2.33.0, < 2.33.12; < 2.29.20", "ecosystem": "go"}]
ecosystems: []
tags: ["api-key", "coder", "other", "self-hosted", "workspace-proxy", "workspaces"]
not_affected_if: ["managed-hosting", "no-workspace-proxies", "version-already-patched"]
published_at: "2026-10-17T19:16:35+00:00"
first_seen_at: "2026-10-23T21:57:14+00:00"
updated_at: "2026-10-24T00:23:27+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-111927", "first_seen_at": "2026-10-23T21:57:14+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-10-24T00:23:27+00:00"}]
---

# Coder: hostname check lets prefix domains steal workspace API keys

Coder trusts any domain that starts with a workspace proxy's access URL, so an attacker-owned look-alike domain can receive a victim's application_connect API key. The attacker can then replay that key to reach the victim's workspace apps.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- go:coder affected >= 2.35.0, < 2.35.4; >= 2.34.0, < 2.34.8; >= 2.33.0, < 2.33.12; < 2.29.20 fixed 2.35.4, 2.34.8, 2.33.12, 2.29.20

## How to check

Run 'coder version' (or check the dashboard footer) on the server: affected if >= 2.35.0 <2.35.4, >= 2.34.0 <2.34.8, >= 2.33.0 <2.33.12, or <2.29.20 (2.30-2.32 are EOL and unpatched). Then run 'coder wsproxy ls' or check Admin > Workspace Proxies: if no workspace proxies are configured, you are not affected.

## Fix

Upgrade to 2.35.4, 2.34.8, 2.33.12 or 2.29.20 for your release line. 2.30-2.32 are EOL with no patch, so move to a supported line. There is no config-only workaround.

## Timeline

- 2026-10-23T21:57:14+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-111927
- 2026-10-24T00:23:27+00:00 analyst — Read Coder GHSA-h58h-qvv5-xvwg (published 2026-08-10) and v2.35.4 release. Needs workspace proxies, an authenticated victim who opens a crafted link, and an attacker domain that is a prefix of a proxy URL. No workaround. No PoC or exploitation found; little X chatter.

## Documents

- [advisory] GHSA-h58h-qvv5-xvwg: Workspace proxy hostname prefix match https://github.com/coder/coder/security/advisories/GHSA-h58h-qvv5-xvwg
- [fix] Coder v2.35.4 https://github.com/coder/coder/releases/tag/v2.35.4

## From the sources

Coder before 2.29.20, 2.33.0 before 2.33.12, 2.34.0 before 2.34.8, and 2.35.0 before 2.35.4 contains an improper hostname validation flaw in GetWorkspaceProxyByHostname whose SIMILAR TO pattern performs a prefix match, so any domain that is a string prefix of a workspace-proxy access URL is trusted as a proxy. Attackers owning such a domain can lure an authenticated victim to a crafted /api/v2/applications/auth-redirect link, capture the redirected application_connect API key, and replay it to access the victim's workspace apps.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_