GHSA-f962-qm93-mj4c CVE-2026-55079 GO-2026-5911
Coder's unbounded memory allocation in provisioner file upload allows authenticated denial of service
- Severity
- 4.9 / 10
- Medium · CVSS 3.1
- Exploit chance (EPSS)
- 0.61%
- Chance of exploitation in the next 30 days. Higher than 49.26% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-789 Memory Allocation with Excessive Size Value
- Fix
2.34.2- Upgrade github.com/coder/coder/v2 to this version or later
Description
Summary
NewDataBuilder in provisionersdk/proto/dataupload.go allocated a byte slice using the client-supplied FileSize from a DataUpload message without an upper-bound check. Although the DRPC wire limit is 4 MiB, the FileSize value itself was unconstrained
Impact
An authenticated user able to reach the provisioner daemon serve endpoint could send a roughly 50-byte message declaring a huge FileSize (for example 1 TiB), triggering an unrecoverable Go out-of-memory abort that terminates coderd. This is a single-message denial of service affecting the entire deployment.
Patches
The fix validates FileSize against an upper bound (MaxFileSize = 100 MiB) before allocation.
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 access to the provisioner daemon serve endpoint to trusted provisioner daemon service accounts.
Resources
- Fix: #25710
Credits
Coder would like to thank Anthropic's Security Team (ANT-2026-22442) for independently disclosing this issue!
Affected versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| github.com/coder/coder | all versions |
No fix yet |
| github.com/coder/coder/v2 | >= 2.34.0, < 2.34.2 |
2.34.2 |
| github.com/coder/coder/v2 | >= 2.33.0, < 2.33.8 |
2.33.8 |
| github.com/coder/coder/v2 | >= 2.30.0, < 2.32.7 |
2.32.7 |
| github.com/coder/coder/v2 | >= 2.24.0, < 2.29.17 |
2.29.17 |
| github.com/coder/coder/v2 | >= 2.24.0, < 2.29.17>= 2.30.0, < 2.32.7>= 2.33.0, < 2.33.8>= 2.34.0, < 2.34.2 |
2.29.172.32.72.33.82.34.2 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
github.com/coder/coder/v2 Go → 2.34.2
- go
go get github.com/coder/coder/v2@v2.34.2 && go mod tidy
Severity breakdown
CVSS 3.1 4.9
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Weakness
CWE-789: Memory Allocation with Excessive Size Value
The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.
How to prevent it
- Implementation, Architecture and Design: Perform adequate input validation against any value that influences the amount of memory that is allocated. Define an appropriate strategy for handling requests that exceed the limit, and consider supporting a configuration option so that the administrator can extend the amount of memory to be used if necessary.
- Operation: Run your program using system-provided resource limits for memory. This might still cause the program to crash or exit, but the impact to the rest of the system will be minimized.
References
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-h58c-xccx-75m3 Coder: Stored HTML injection via unescaped ApplicationName and LogoURL appearance settings | Medium | Also affects github.com/coder/coder |
| GHSA-8fxq-53rx-ph5f Coder: Login endpoint user enumeration via timing-defense placeholder in password comparison | Medium | Also affects github.com/coder/coder |
| GHSA-qrwj-vh9x-gw5v Coder's workspace agent API insecure redirect handling allowed cross-agent file read and write | High | Also affects github.com/coder/coder |
| GHSA-5wg6-jmq2-53pw Coder's workspace app CORS origin check can be bypassed via UUID-based subdomain spoofing | Medium | Also affects github.com/coder/coder |
| GHSA-7qw2-f75v-62f7 Coder vulnerable to stored HTML injection via workspace agent logs in AgentLogLine component | Medium | Also affects github.com/coder/coder |
| GHSA-84rm-42xw-mx52 Coder's AI Bridge Proxy skips TLS certificate verification in default configuration | High | Also affects github.com/coder/coder |
| GHSA-wqxv-w64v-5wh6 Suspended Coder users retain access to AI Bridge LLM proxy endpoints | Medium | Also affects github.com/coder/coder |
| GHSA-f5vp-w269-392g Coder vulnerable to denial of service via unbounded request body in AI Bridge provider endpoints | Medium | Also affects github.com/coder/coder |
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