util-linux libmount Privilege Escalation via Failed Mount Helper
Summary
| CVE | CVE-2026-76642 |
|---|---|
| State | PUBLISHED |
| Assigner | VulnCheck |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-03 13:06:08 UTC |
| Updated | 2026-09-03 15:17:33 UTC |
| Description | util-linux versions through 2.41.5 and 2.42.2 fail to check mount helper exit status before running post-mount hooks, allowing unprivileged users to execute privileged operations on pre-existing filesystems. Attackers can exploit X-mount.idmap or X-mount.owner hooks to clone filesystems with inherited suid bits or modify target inode permissions after a helper fails, achieving privilege escalation. |
Risk And Classification
Primary CVSS: v4.0 8.5 HIGH from [email protected]
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.001760000 probability, percentile 0.072300000 (date 2026-09-07)
Problem Types: CWE-390 | CWE-390 Detection of Error Condition Without Action
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 8.5 | HIGH | CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 8.5 | HIGH | CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
| 3.1 | [email protected] | Secondary | 7.8 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | CNA | CVSS | 7.8 | HIGH | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
CVSS v4.0 Breakdown
Attack Vector
LocalAttack Complexity
LowAttack Requirements
NonePrivileges Required
LowUser Interaction
NoneConfidentiality
HighIntegrity
HighAvailability
HighSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
Attack Vector
LocalAttack Complexity
LowPrivileges Required
LowUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Util-linux | Util-linux | affected 2.39 2.41.6 custom | Not specified |
| CNA | Util-linux | Util-linux | affected 2.42 2.42.3 custom | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/context_mount.c | [email protected] | github.com | |
| github.com/util-linux/util-linux/commit/a15c00a9e545aa8b9cf6ec0f888ff6c7... | [email protected] | github.com | |
| www.vulncheck.com/advisories/util-linux-libmount-privilege-escalation-via-faile... | [email protected] | www.vulncheck.com | |
| github.com/util-linux/util-linux/commit/1d14676ea70003e9f5b2a6a76af0cadb... | [email protected] | github.com | |
| github.com/util-linux/util-linux/blob/v2.42.2/libmount/src/context_mount.c | [email protected] | github.com | |
| github.com/util-linux/util-linux | [email protected] | github.com | |
| github.com/util-linux/util-linux/commit/f57cea130839c0af8dc0525274267ae4... | [email protected] | github.com | |
| github.com/util-linux/util-linux/security/advisories/GHSA-m25x-3hj9-m26f | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | github.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Andreas Gabriel Berbescu (en)
CNA: Ivan Redondo Plaza (en)
There are currently no legacy QID mappings associated with this CVE.