Incorrect Authorization Affecting github.com/coder/coder/v2/tailnet package, versions <2.29.17>=2.30.0 <2.32.7>=2.33.0 <2.33.8>=2.34.0 <2.34.2
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published6 Jul 2026
- disclosed6 Jul 2026
- creditUnknown
Introduced: 6 Jul 2026
CVE-2026-55428 Â (opens in a new tab)How to fix?
Upgrade github.com/coder/coder/v2/tailnet to version 2.29.17, 2.32.7, 2.33.8, 2.34.2 or higher.
Overview
Affected versions of this package are vulnerable to Incorrect Authorization in the AllowedIPs process. An attacker can intercept network traffic and serve spoofed content by supplying arbitrary AllowedIPs prefixes, allowing them to claim another agent's tailnet address. This is only exploitable if an authenticated user has a running workspace and uses a modified agent binary.
Workaround
This vulnerability can be mitigated by monitoring coordinator logs for agents advertising unexpected AllowedIPs prefixes.