CVE
Coder session token leak in dashboard app URLs
Affects Coder 2.38.0 before 2.38.2 when code runs as a sub-agent in the workspace, such as a devcontainer or AI agent. Fixed in 2.38.2.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 2.38.2, 2.37.6, 2.36.9, 2.34.14, 2.29.23, and 1 more
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. Coder web dashboard in affected versions 2.24.0 through 2.38.x before the patched releases Attacker runs code as a sub-agent in the victim's workspace, such as a devcontainer or AI agent
- Published
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 17/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
The web dashboard in Coder 2.24.0 before 2.29.23, 2.30.0 before 2.34.14, 2.35.0 before 2.36.9, 2.37.0 before 2.37.6, and 2.38.0 before 2.38.2 replaces the $SESSION_TOKEN placeholder in external app URLs with a full-access API key without checking whether the app belongs to a sub-agent. Code running in a workspace can register a disguised sub-agent app with a custom protocol URL, so the owner's click sends their API key to an attacker-chosen destination.
Who should check
Teams running Coder 2.24.0 through 2.38.x web dashboards where users open external apps from sub-agents such as devcontainers or AI agents in workspaces
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure8/25Specific setups only, reachable over the network
- Reach?/20Unknown. No tracked technology or package matched
- Severity8.7/10CVSS 8.7
- No patch0/5No signal
What would change the score
- Would score about 67 if added to CISA KEV
- Would score about 62 if CISA's SSVC rates exploitation active
- Would score about 24 if CISA's SSVC rates it automatable
What to do
Check whether your setup matches what the bug needs.
Coder web dashboard in affected versions 2.24.0 through 2.38.x before the patched releases Attacker runs code as a sub-agent in the victim's workspace, such as a devcontainer or AI agentUpgrade to a fixed version: 2.38.2, 2.37.6, 2.36.9, 2.34.14, 2.29.23, or one of 1 more.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
Check whether my systems are affected by CVE-2026-126308 (Coder 2.38.0 before 2.38.2 Session Token Leak via Sub-Agent External Apps), using the cve.now data below.
Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.
What cve.now has for CVE-2026-126308 (entry last updated 2026-11-13):
Affected:
- coder coder: from 2.38.0, fixed in 2.38.2
- coder coder: from 2.37.0, fixed in 2.37.6
- coder coder: from 2.36.0, fixed in 2.36.9
- coder coder: from 2.30.0, fixed in 2.34.14
- coder coder: from 2.24.0, fixed in 2.29.23
- coder coder: from 2.35.0, fixed in 2.36.0
Fixed versions: 2.38.2, 2.37.6, 2.36.9, 2.34.14, 2.29.23, 2.36.0.
Conditions (all must be true for the bug to be hit):
- Coder web dashboard in affected versions 2.24.0 through 2.38.x before the patched releases (source: https://www.vulncheck.com/advisories/coder-2.38.0-before-2.38.2-session-token-leak-via-sub-agent-external-apps)
- Attacker runs code as a sub-agent in the victim's workspace, such as a devcontainer or AI agent (source: https://github.com/coder/coder/security/advisories/GHSA-2x8w-q434-f76p)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: network access, low-privilege login, a user action.
CISA KEV: CVE-2026-126308 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126308 only. If you also check another CVE, look up its own KEV status; never assume it from this one.
How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.
Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/coder/coder/security/advisories/GHSA-2x8w-q434-f76p
- https://www.vulncheck.com/advisories/coder-2.38.0-before-2.38.2-session-token-leak-via-sub-agent-external-apps
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.
Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.
Entry: https://cve.now/CVE-2026-126308
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-126308"}.Timeline
- CVE published
- First seen by cve.now
Affected versions
- coder coder
From 2.38.0 · fixed in 2.38.2
- coder coder
From 2.37.0 · fixed in 2.37.6
- coder coder
From 2.36.0 · fixed in 2.36.9
- coder coder
From 2.30.0 · fixed in 2.34.14
- coder coder
From 2.24.0 · fixed in 2.29.23
- coder coder
From 2.35.0 · fixed in 2.36.0
Evidence 4
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-126308
Is CVE-2026-126308 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
Code running as a sub-agent in a Coder workspace can obtain a full-access API key belonging to the workspace owner. With that key, an attacker can act as that user for the key's lifetime.Source: vulncheck.com, github.com
Which versions are affected by CVE-2026-126308?
coder: from 2.38.0 before 2.38.2. coder: from 2.37.0 before 2.37.6. coder: from 2.36.0 before 2.36.9. coder: from 2.30.0 before 2.34.14. coder: from 2.24.0 before 2.29.23. 1 more package is listed on the page.Source: cve.now feed data
Am I affected, and how do I check?
The listed ranges are Coder 2.24.0 before 2.29.23, 2.30.0 before 2.34.14, 2.35.0 before 2.36.0, 2.36.0 before 2.36.9, 2.37.0 before 2.37.6, and 2.38.0 before 2.38.2. The setup that matters is a sub-agent running in the workspace, such as a devcontainer or AI agent, and the version can be checked with the coder version command.Source: vulncheck.com, github.com
How do I fix CVE-2026-126308?
Upgrade to the fixed release for your version line: 2.38.2, 2.37.6, 2.36.9, 2.34.14, or 2.29.23. The facts do not give a workaround or vendor patch identifiers.Source: vulncheck.com, github.com