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NVD / CVE Program· CNA GitHub_M

CVE-2026-27456: util-linux: TOCTOU Race Condition in util-linux mount(8) - Loop Device Setup

MediumCVSS 4.7 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 18/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.15% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: util-linux util-linux 2.41.4; azl3 util-linux 2.40.2-3 on Azure Linux 3.0 2.40.2-4; azl3 util-linux 2.40.2-4 on Azure Linux 3.0 2.40.2-4.

Low priority for now. Upgrade to util-linux util-linux 2.41.4; azl3 util-linux 2.40.2-3 on Azure Linux 3.0 2.40.2-4; azl3 util-linux 2.40.2-4 on Azure Linux 3.0 2.40.2-4 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

util-linux is a random collection of Linux utilities. Prior to version 2.41.4, a TOCTOU (Time-of-Check-Time-of-Use) vulnerability has been identified in the SUID binary /usr/bin/mount from util-linux. The mount binary, when setting up loop devices, validates the source file path with user privileges via fork() + setuid() + realpath(), but subsequently re-canonicalizes and opens it with root privileges (euid=0) without verifying that the path has not been replaced between both operations. Neither O_NOFOLLOW, nor inode comparison, nor post-open fstat() are employed. This allows a local unprivileged user to replace the source file with a symlink pointing to any root-owned file or device during the race window, causing the SUID binary to open and mount it as root. Exploitation requires an /etc/fstab entry with user,loop options whose path points to a directory where the attacker has write permission, and that /usr/bin/mount has the SUID bit set (the default configuration on virtually all Linux distributions). The impact is unauthorized read access to root-protected files and block devices, including backup images, disk volumes, and any file containing a valid filesystem. This issue has been patched in version 2.41.4.

Published
Apr 3, 2026
Updated
Jul 24, 2026
EPSS
0.1% · 4th percentile

Report tools

JSON

Action score

18

Monitor

Low priority for now.

CVSS
18 / 40 · 4.7 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
proof of concept
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
4.7
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
kernelutil-linux

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • util-linux util-linux

    • < 2.41.4affected

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • kernel util-linuxbefore 2.41.4

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
AlmaLinux:10libblkidbefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
AlmaLinux:10libblkid-develbefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
AlmaLinux:10libfdiskbefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
AlmaLinux:10libfdisk-develbefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
AlmaLinux:10libmountbefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
AlmaLinux:10libmount-develbefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
AlmaLinux:10libsmartcolsbefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
AlmaLinux:10libsmartcols-develbefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
AlmaLinux:10libuuidbefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
AlmaLinux:10libuuid-develbefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
AlmaLinux:10python3-libmountbefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
AlmaLinux:10util-linuxbefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
AlmaLinux:10util-linux-corebefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
AlmaLinux:10uuiddbefore 2.40.2-18.el10_2.202.40.2-18.el10_2.20
Alpine:v3.22util-linuxbefore 2.41.6-r02.41.6-r0
Alpine:v3.23util-linuxbefore 2.41.4-r02.41.4-r0
Alpine:v3.24util-linuxbefore 2.42.3-r02.42.3-r0
Debian:12util-linuxfrom 0—
Debian:13util-linuxbefore 2.41.5-0+deb13u12.41.5-0+deb13u1
Debian:14util-linuxbefore 2.42-12.42-1
openSUSE:Leap 16.0python-libmountbefore 2.41.1-160000.4.12.41.1-160000.4.1
openSUSE:Leap 16.0python-libmountbefore 2.41.1-160000.5.12.41.1-160000.5.1
openSUSE:Leap 16.0util-linuxbefore 2.41.1-160000.5.12.41.1-160000.5.1
openSUSE:Leap 16.0util-linuxbefore 2.41.1-160000.4.12.41.1-160000.4.1

+36

Same product

kernel: all records

Other highest-scoring records for the same primary product.

  • CVE-2015-5224The mkostemp function in login-utils in util-linux when used incorrectly allows remote attackers to cause file name collision and possibly…
    40Plan
  • CVE-2018-7738In util-linux before 2.32-rc1, bash-completion/umount allows local users to gain privileges by embedding shell commands in a mountpoint…
    31Monitor
  • CVE-2016-2779runuser in util-linux allows local users to escape to the parent session via a crafted TIOCSTI ioctl call, which pushes characters to the…
    31Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2020-21583Aug 22, 2023 · An issue was discovered in hwclock.13-v2.27 allows attackers to gain escalated privlidges or execute arbitrary commands via the path…
    26Monitor
  • ← EarlierCVE-2024-28085Mar 27, 2024 · wall in util-linux through 2.40, often installed with setgid tty permissions, allows escape sequences to be sent to other users' terminals…
    14Monitor
  • Later →CVE-2026-3184Apr 3, 2026 · Util-linux: util-linux: access control bypass due to improper hostname canonicalization
    21Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
util-linux util-linux2.41.4 · descriptionVendor (CNA)
azl3 util-linux 2.40.2-3 on Azure Linux 3.02.40.2-4 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 util-linux 2.40.2-4 on Azure Linux 3.02.40.2-4 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 util-linux 2.37.4-10 on CBL Mariner 2.02.37.4-11 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 util-linux 2.37.4-10 on CBL-Mariner 2.02.37.4-11 · Release NotesMicrosoft (MSRC)
almalinux:libblkid2.40.2-18.el10_2.20 · AlmaLinux:10Package registry (OSV)
almalinux:libblkid-devel2.40.2-18.el10_2.20 · AlmaLinux:10Package registry (OSV)
almalinux:libfdisk2.40.2-18.el10_2.20 · AlmaLinux:10Package registry (OSV)
almalinux:libfdisk-devel2.40.2-18.el10_2.20 · AlmaLinux:10Package registry (OSV)
almalinux:libmount2.40.2-18.el10_2.20 · AlmaLinux:10Package registry (OSV)
almalinux:libmount-devel2.40.2-18.el10_2.20 · AlmaLinux:10Package registry (OSV)
almalinux:libsmartcols2.40.2-18.el10_2.20 · AlmaLinux:10Package registry (OSV)
almalinux:libsmartcols-devel2.40.2-18.el10_2.20 · AlmaLinux:10Package registry (OSV)
almalinux:libuuid2.40.2-18.el10_2.20 · AlmaLinux:10Package registry (OSV)
almalinux:libuuid-devel2.40.2-18.el10_2.20 · AlmaLinux:10Package registry (OSV)
almalinux:python3-libmount2.40.2-18.el10_2.20 · AlmaLinux:10Package registry (OSV)
almalinux:util-linux2.40.2-18.el10_2.20 · AlmaLinux:10Package registry (OSV)
alpine:util-linux2.41.6-r0 · Alpine:v3.22Package registry (OSV)
debian:util-linux2.41.5-0+deb13u1 · Debian:13Package registry (OSV)
opensuse:python-libmount2.41.1-160000.4.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:util-linux2.42-1.1 · openSUSE:TumbleweedPackage registry (OSV)
opensuse:util-linux-systemd2.41.1-160000.4.1 · openSUSE:Leap 16.0Package registry (OSV)
red hat:libblkid0:2.42-7.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:util-linux0:2.42-7.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:util-linux-core0:2.42-7.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:util-linux-i18n0:2.42-7.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:util-linux-script0:2.42-7.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
rocky linux:util-linux0:2.40.2-18.el10_2.20 · Rocky Linux:10Package registry (OSV)
suse:python-libmount2.41.1-160000.4.1 · SUSE:Linux Enterprise Server 16.0Package registry (OSV)
suse:util-linux2.41.1-160000.4.1 · SUSE:Linux Micro 6.2Package registry (OSV)

+1

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Not on record for this CVE: EPSS history · researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
none
Attack vector
Local
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-59 · Improper Link Resolution Before File Access ('Link Following')

CVSS vector

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records