CVE-2026-32282: TOCTOU permits root escape on Linux via Root.Chmod in os in internal/syscall/unix

Severity: medium (CVSS 6.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-08 · updated 2026-07-25
Weakness: CWE-59

Description

On Linux, if the target of Root.Chmod is replaced with a symlink while the chmod operation is in progress, Chmod can operate on the target of the symlink, even when the target lies outside the root. The Linux fchmodat syscall silently ignores the AT_SYMLINK_NOFOLLOW flag, which Root.Chmod uses to avoid symlink traversal. Root.Chmod checks its target before acting and returns an error if the target is a symlink lying outside the root, so the impact is limited to cases where the target is replaced with a symlink between the check and operation.

Affected products

Go: before 1.25.9; from 1.26.0 before 1.26.2 — fixed in 1.25.9, 1.26.2
Go Stdlib: before 1.25.9; from 1.26.0-0 before 1.26.2 — fixed in 1.25.9, 1.26.2

How to fix

Upgrade to a fixed version: Go 1.25.9, 1.26.2; Go Stdlib 1.25.9, 1.26.2. Check the vendor advisory for mitigations.

References

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