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Vulnerability record · CVE-2026-55438 · published 8 July 2026

CVE-2026-55438: Coder origin validation error vulnerability

Coder · Coder

Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.17, 2.32.7, 2.33.8, and 2.34.2, Coder's subdomain-based workspace app proxy allowed the same-owner CORS check to be bypassed. When a workspace-name subdomain segment parsed as a UUID, the workspace was resolved by ID without confirming the URL's username matched the real owner, while the CORS middleware trusted the unverified username in the hostname. Practical exploitation requires subdomain app routing (wildcard hostname) enabled and a victim who visits the attacker's crafted app URL while authenticated. The fix in versions 2.29.17, 2.32.7, 2.33.8, and 2.34.2 validates the subdomain username against the resolved workspace's actual owner and bases the same-owner CORS decision on the authoritative owner identity. No known workarounds are available.

6.8 CVSS 3.1 Medium EPSS 0.22% · top 88.4% CWE-346 · Origin validation error
6.8CVSS 3.1 base score
0.22%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
7References
8 Jul 2026Last modified by NVD

Description

Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.17, 2.32.7, 2.33.8, and 2.34.2, Coder's subdomain-based workspace app proxy allowed the same-owner CORS check to be bypassed. When a workspace-name subdomain segment parsed as a UUID, the workspace was resolved by ID without confirming the URL's username matched the real owner, while the CORS middleware trusted the unverified username in the hostname. Practical exploitation requires subdomain app routing (wildcard hostname) enabled and a victim who visits the attacker's crafted app URL while authenticated. The fix in versions 2.29.17, 2.32.7, 2.33.8, and 2.34.2 validates the subdomain username against the resolved workspace's actual owner and bases the same-owner CORS decision on the authoritative owner identity. No known workarounds are available.

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/coder/coder/pull/26085 Issue TrackingPatch
https://github.com/coder/coder/pull/26086 Issue TrackingPatch
https://github.com/coder/coder/releases/tag/v2.29.17 Release Notes
https://github.com/coder/coder/releases/tag/v2.32.7 Release Notes
https://github.com/coder/coder/releases/tag/v2.33.8 Release Notes
https://github.com/coder/coder/releases/tag/v2.34.2 Release Notes
https://github.com/coder/coder/security/advisories/GHSA-5wg6-jmq2-53pw PatchVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-55438), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.