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Fencer Vulns
high 7.7

CVE-2026-55431 json

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

published 2026-07-06 4 mo ago modified 2026-07-08 4 mo ago also GHSA-v54h-cp2w-9x4g , GO-2026-5924 , EUVD-2026-42140

cvss
7.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 27%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/coder/coder/v2 2.29.17, 2.32.7, 2.33.8, 2.34.2
  • coder coder 2.29.17, 2.32.7, 2.33.8, 2.34.2
  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
4 mo ago

Exploit prediction

0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.7 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
GitHub 3.1 7.7 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N

Affected packages

ecosystem package affected fixed in
go github.com/coder/coder/v2
>=2.34.0, <2.34.2
>=2.33.0, <2.33.8
>=2.30.0, <2.32.7
<2.29.17
2.34.2
2.33.8
2.32.7
2.29.17
go github.com/coder/coder
all versions
 no fix listed

Affected products

  • coder coder

Classification

Weakness
  • CWE-522 Insufficiently Protected Credentials
  • CWE-601 URL Redirection to Untrusted Site

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.