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TI-2026-54521 Aliases CVE-2026-78408

Util-linux: util-linux: nsenter --join-cgroup leaks root cgroup migration authority

Priority HIGH 68CWE-775Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
Required
Attack complexity
Low
Impact type
—
Confidentiality · integrity · availability
None · High · High
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.

Summary

The nsenter --join-cgroup option opens the target cgroup.procs file as root and leaves that file descriptor open across later namespace and credential changes and across execve(). Because the kernel checks later cgroup migrations using the credentials from the original open, a program run in an attacker-controlled target can inherit root's ability to move host processes between cgroups. After a privileged operator uses --join-cgroup against that target, an unprivileged user can migrate and terminate unrelated root processes.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00237 14th percentileScored 2026-11-07
Fix Fixed Red Hat: 3 advisories

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
Red HatRed Hat Enterprise Linux 10—2.40.2-18.el10_2.20Patch availableCNA
Red HatRed Hat Cost Management On-Premise 1—1793825318Patch availableCNA
Red HatRed Hat Hardened Images—2.42.2-3.4.hum1Patch availableCNA
Red HatRed Hat Enterprise Linux 7——Not affectedCNA
Red HatRed Hat Enterprise Linux 8——Not affectedCNA
Red HatRed Hat Enterprise Linux 9——Not affectedCNA
Red HatRed Hat Enterprise Linux 9——Not affectedCNA
Red HatRed Hat Enterprise Linux 9——Not affectedCNA
Red HatRed Hat OpenShift Container Platform 4——Not affectedCNA
Red HatRed Hat OpenShift Container Platform 4——Not affectedCNA
Red HatRed Hat OpenShift Container Platform 5——Not affectedCNA
  • Red Hat Enterprise Linux 10 VendorRed Hat Affected — Fixed in 2.40.2-18.el10_2.20 Patch available CNA
  • Red Hat Cost Management On-Premise 1 VendorRed Hat Affected — Fixed in 1793825318 Patch available CNA
  • Red Hat Hardened Images VendorRed Hat Affected — Fixed in 2.42.2-3.4.hum1 Patch available CNA
  • Red Hat Enterprise Linux 7 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat Enterprise Linux 8 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat Enterprise Linux 9 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat OpenShift Container Platform 4 VendorRed Hat Affected — Fixed in — Not affected CNA
  • Red Hat OpenShift Container Platform 5 VendorRed Hat Affected — Fixed in — Not affected CNA

CPE names CNA · 8

CPEVersionsRoleVendor
cpe:/o:redhat:enterprise_linux:10.210.2—Red Hat
cpe:/a:redhat:cost_management_on_premise:1::el101—Red Hat
cpe:/a:redhat:hummingbird:11—Red Hat
cpe:/o:redhat:rhel_els:77—Red Hat
cpe:/a:redhat:enterprise_linux:88—Red Hat
cpe:/a:redhat:enterprise_linux:99—Red Hat
cpe:/a:redhat:openshift:44—Red Hat
cpe:/a:redhat:openshift:55—Red Hat
  • cpe:/o:redhat:enterprise_linux:10.2 Versions 10.2 — ·Red Hat
  • cpe:/a:redhat:cost_management_on_premise:1::el10 Versions 1 — ·Red Hat
  • cpe:/a:redhat:hummingbird:1 Versions 1 — ·Red Hat
  • cpe:/o:redhat:rhel_els:7 Versions 7 — ·Red Hat
  • cpe:/a:redhat:enterprise_linux:8 Versions 8 — ·Red Hat
  • cpe:/a:redhat:enterprise_linux:9 Versions 9 — ·Red Hat
  • cpe:/a:redhat:openshift:4 Versions 4 — ·Red Hat
  • cpe:/a:redhat:openshift:5 Versions 5 — ·Red Hat

Remediation

Red Hat 3 advisories

  • RHSA-2026:95365 Released 2026-11-04 · Red Hat rating Critical
    Red Hat Cost Management On-Premise container image update
    • Red Hat Cost Management On-Premise 1 registry.redhat.io/costmanagement/costmanagement-ui-rhel10
  • RHSA-2026:93461 Released 2026-11-02 · Red Hat rating Important
    util-linux security update
    • Red Hat Enterprise Linux AppStream (v. 10) libblkid-devel-2.40.2-18.el10_2.20, libmount-devel-2.40.2-18.el10_2.20, libuuid-devel-2.40.2-18.el10_2.20 +2
    • Red Hat Enterprise Linux BaseOS (v. 10) libblkid-2.40.2-18.el10_2.20, libfdisk-2.40.2-18.el10_2.20, libmount-2.40.2-18.el10_2.20 +4
    • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libfdisk-devel-2.40.2-18.el10_2.20, libsmartcols-devel-2.40.2-18.el10_2.20
  • RHSA-2026:63162 Released 2026-09-03 · Red Hat rating Important
    Red Hat Hardened Images RPMs Security Update
    • Red Hat Hardened Images libblkid-2.42.2-3.4.hum1@aarch64, libblkid-2.42.2-3.4.hum1@x86_64, libblkid-devel-2.42.2-3.4.hum1@aarch64 +34

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Advisory ·

    Red Hat Cost Management On-Premise 1, Red Hat Enterprise Linux 10 and 6 more products — RHSA-2026:63162

    3 records Highest priority Priority HIGH 3 HIGH

    Other records, highest priority first

    • TI-2026-54523 Util-linux: util-linux: restricted bind mounts do not pin the source, allowing x-mount.owner/group/mode redirectionPriority HIGH 69
    • TI-2026-54522 Util-linux: util-linux: x-mount.subdir detached-tree resolution can escape via intermediate symlinksPriority HIGH 66
    Show all 3 records → Advisory →

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Cost Management On-Premise 1Fixed RHSA-2026:95365
Red Hat Enterprise Linux AppStream (v. 10)Fixed RHSA-2026:93461
Red Hat Enterprise Linux BaseOS (v. 10)Fixed RHSA-2026:93461
Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)Fixed RHSA-2026:93461
Red Hat Hardened ImagesFixed RHSA-2026:63162
Not affected: 5 products
  • Red Hat Enterprise Linux 7
  • Red Hat Enterprise Linux 8
  • Red Hat Enterprise Linux 9
  • Red Hat OpenShift Container Platform 4
  • Red Hat OpenShift Container Platform 5

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-78408
  2. 2026-10-21 Affected versions changed · CNA
  3. 2026-10-30 Affected versions changed · CNA
  4. 2026-10-30 Affected versions changed · Red Hat
  5. 2026-11-02 Fix available: util-linux@0:2.40.2-18.el10_2.20 · CNA
  6. 2026-11-02 1 new reference · CNA
  7. 2026-11-02 Fix available: RHSA-2026:93461 · Red Hat
  8. 2026-11-02 Fix available: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) · Red Hat
  9. 2026-11-05 Fix available: costmanagement/costmanagement-ui-rhel10@1793825318 · CNA
  10. 2026-11-05 1 new reference · CNA
  11. 2026-11-05 Fix available: Red Hat Cost Management On-Premise 1 · Red Hat
  12. 2026-11-06 Fix available: RHSA-2026:95365 · Red Hat

References

Advisory 3

Other 3

  • TI-2019-15875 Protection mechanism failure in Jenkins Pipeline: Groovy Plugin KEVCVSS 3.1CRITICAL 9.9
  • TI-2019-15874 Protection mechanism failure in Jenkins Script Security Plugin KEVCVSS 3.1CRITICAL 9.9
  • TI-2019-08259 Underflow in PHP-FPM can lead to RCE KEVCVSS 3.1CRITICAL 9.8
  • TI-2019-05363 Code injection in Elastic Kibana KEVCVSS 3.1CRITICAL 10.0
  • TI-2019-03949 Out-of-bounds write in ESXi and Horizon DaaS KEVCVSS 3.1CRITICAL 9.8
  • TI-2018-16080 A code execution vulnerability exists in the Stapler web framework used by Jenkins 2.153… KEVCVSS 3.1CRITICAL 9.8
See all 7413 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences