TOCTOU permits root escape on Linux via Root.Chmod in os in internal/syscall/unix
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.
GO-2026-4864
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:GO-2026-4864
stdlib
Source reference: /affected/0/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 1.25.9
Source reference:
/affected/0/ranges1.26.2Source reference:
/affected/0/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"type": "SEMVER",
"events": [
{
"introduced": "0"
},
{
"fixed": "1.25.9"
},
{
"introduced": "1.26.0-0"
},
{
"fixed": "1.26.2"
}
]
}
],
"package": {
"name": "stdlib",
"purl": "pkg:golang/stdlib",
"ecosystem": "Go"
},
"database_specific": {
"source": "https://vuln.go.dev/ID/GO-2026-4864.json"
},
"ecosystem_specific": {
"imports": [
{
"goos": [
"linux"
],
"path": "internal/syscall/unix",
"symbols": [
"Fchmodat"
]
}
]
}
}
]- Related CVEs
- CVE-2026-32282
Source reference:
/aliases
Publisher severity
No explicit severity was provided.
- Event
- #27678 · Revision 1
- Added to Heist Feed
- Publisher date