Vulnerability · Published Jul 8, 2026 · Assigned by GitHub_M

CVE-2026-55431Coder's session token leaked to arbitrary hosts via `coder open app` for external workspace apps

High 7.7

In plain English

A high-severity open redirect in coder from coder. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.7High

Exploit odds (30 days)0.3%top 72.9% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, `coder open app` opens external workspace-app URLs without validating the scheme or host. When an external app URL contains the `$SESSION_TOKEN` placeholder the CLI replaces it with the user's real session token before handing the URL to the OS open handler. Practical exploitation requires the victim to run `coder open app` against a workspace whose external app definition the attacker controls. Only a malicious template author can control external app URLs. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 applies a URL-scheme allowlist in the CLI and limits `$SESSION_TOKEN` substitution to trusted destinations like the web frontend. As a workaround, avoid running `coder open app` for untrusted workspaces.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/coder/coder	no fix listed	GO-2026-5924
Go	github.com/coder/coder/v2	2.29.17, 2.32.7, 2.33.8, 2.34.2	GO-2026-5924
Go	github.com/coder/coder/v2	2.34.2	GHSA-v54h-cp2w-9x4g
Go	github.com/coder/coder/v2	2.33.8	GHSA-v54h-cp2w-9x4g
Go	github.com/coder/coder/v2	2.32.7	GHSA-v54h-cp2w-9x4g
Go	github.com/coder/coder/v2	2.29.17	GHSA-v54h-cp2w-9x4g

Affected products (as reported)

Vendor	Product	Versions
coder	coder	>= 2.34.0, < 2.34.2>= 2.33.0, < 2.33.8>= 2.30.0, < 2.32.7< 2.29.17

Weakness: CWE-522, CWE-601 · Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N

References

https://github.com/coder/coder/security/advisories/GHSA-v54h-cp2w-9x4g x_refsource_CONFIRM
https://github.com/coder/coder/pull/26146 x_refsource_MISC
https://github.com/coder/coder/releases/tag/v2.29.17 x_refsource_MISC
https://github.com/coder/coder/releases/tag/v2.32.7 x_refsource_MISC
https://github.com/coder/coder/releases/tag/v2.33.8 x_refsource_MISC
https://github.com/coder/coder/releases/tag/v2.34.2 x_refsource_MISC