CVE-2026-55434: Coder vulnerable to denial of service via unbounded request body in AI Bridge provider endpoints
Summary
AI Bridge provider handlers read request bodies with io.ReadAll without a maximum size so an authenticated user with AI Bridge access could send an arbitrarily large body and exhaust memory.
Note: Exploitation requires authenticated access to the AI Bridge endpoints and the impact is limited to availability (denial of service).
Impact
An authenticated member-level user could POST a very large or chunked body to an AI Bridge provider endpoint such as /api/v2/aibridge/anthropic/v1/messages, growing heap memory until the operating system terminates the process. Because AI Bridge runs in-process with coderd, this crashes the entire control plane, including the API, workspace coordinator and DERP relay. It requires an authenticated user and the AI Bridge feature enabled.
Patches
The fix applies http.MaxBytesReader or an equivalent cap before reading provider and session request bodies. The affected AI Bridge provider endpoints exist only on the v2.33 and v2.34 lines. Earlier release lines are not affected.
The fix is available in the following releases:
| Release line | Patched version | |---|---| | 2.34 | v2.34.2 | | 2.33 | v2.33.8 |
Workarounds
None.
Resources
- Fix: #26164
Credits
Coder would like to thank Anthropic's Security Team (ANT-2026-22443) for independently disclosing this issue!
Other sources
Coder allows organizations to provision remote development environments via Terraform. Starting in version 2.33.0 and prior to versions 2.33.8 and 2.34.2, AI Bridge provider handlers read request bodies with io.ReadAll without a maximum size so an authenticated user with AI Bridge access could send an arbitrarily large body and exhaust memory. Exploitation requires authenticated access to the AI Bridge endpoints and the impact is limited to availability (denial of service). Versions 2.33.8 and 2.34.2 patch the issue. No known workarounds are available.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
go/github.com/coder/coder/v2to a version that resolves this vulnerability.Fixed in 2.33.8 - Upgrade
Upgrade
go/github.com/coder/coder/v2to a version that resolves this vulnerability.Fixed in 2.34.2 - Upgrade
Upgrade
coder/coderto a version that resolves this vulnerability.Fixed in 2.33.8 - Upgrade
Upgrade
coder/coderto a version that resolves this vulnerability.Fixed in 2.34.2
Event History
Frequently Asked Questions
What is the severity of CVE-2026-55434?
The severity of CVE-2026-55434 is rated as medium with a CVSS score of 6.5.
How does CVE-2026-55434 affect my system?
CVE-2026-55434 allows an authenticated user to send an arbitrarily large request body, potentially exhausting system memory.
What are the potential impacts of exploiting CVE-2026-55434?
Exploitation of CVE-2026-55434 could lead to a denial of service by consuming server memory.
How do I mitigate CVE-2026-55434?
To mitigate CVE-2026-55434, implement input size validation and set a maximum request body size for the AI Bridge endpoints.
Is authentication required to exploit CVE-2026-55434?
Yes, exploitation of CVE-2026-55434 requires authenticated access to the AI Bridge endpoints.