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Coder: Stored HTML injection via unescaped ApplicationName and LogoURL appearance settings

Low severity GitHub Reviewed Published Jun 12, 2026 in coder/coder • Updated Aug 20, 2026

Package

gomod github.com/coder/coder/v2 (Go)

Affected versions

>= 2.34.0, < 2.34.2
>= 2.33.0, < 2.33.8
>= 2.30.0, < 2.32.7
< 2.29.17

Patched versions

2.34.2
2.33.8
2.32.7
2.29.17

Description

Summary

The ApplicationName and LogoURL appearance settings were rendered into HTML output without sufficient escaping which let a highly privileged Owner-role user inject HTML into the Coder dashboard and SMTP notification emails.

Note: Exploitation requires the Owner role which already holds full administrative control of the deployment so practical impact is limited.

Impact

An Owner-role user could store HTML markup in the ApplicationName or LogoURL appearance settings that later rendered in the dashboard and in SMTP notification emails which results in stored HTML injection against other users of the deployment. Exploitation requires the highly privileged Owner role.

Patches

The fix escapes the ApplicationName and LogoURL appearance values in HTML output before rendering.

The fix was backported to all supported release lines:

Release line Patched version
2.34 v2.34.2
2.33 v2.33.8
2.32 v2.32.7
2.29 (ESR) v2.29.17

Workarounds

Restrict the Owner role to trusted administrators.

References

  • Fix: #25804

Credits

We'd like to thank Anthropic's Security Team (ANT-2026-22453) for independently disclosing this issue!

References

@jdomeracki-coder jdomeracki-coder published to coder/coder Jun 12, 2026
Published to the GitHub Advisory Database Aug 20, 2026
Reviewed Aug 20, 2026
Last updated Aug 20, 2026

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
High
User interaction
Required
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:N/I:L/A:N

EPSS score

Weaknesses

Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component. Learn more on MITRE.

CVE ID

No known CVE

GHSA ID

GHSA-h58c-xccx-75m3

Source code

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