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libcap CVE-2026-4878

| EUVDEUVD-2026-20910 HIGH
Time-of-check Time-of-use (TOCTOU) Race Condition (CWE-367)
2026-04-09 redhat
7.0
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
7.0 HIGH
AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
7.0 HIGH

Local unprivileged user (AV:L, PR:L) must win a TOCTOU race (AC:H) with no user interaction; successful capability injection yields full root, so C:H/I:H/A:H.

3.1 AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
4.0 AV:L/AC:H/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE
6.7 MEDIUM
AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
Red Hat
6.7 HIGH
qualitative

Primary rating from NVD.

CVSS VectorNVD

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

8
Analysis Updated
Jun 11, 2026 - 10:28 vuln.today
v3 (cvss_changed)
Analysis Updated
Jun 11, 2026 - 10:28 vuln.today
v2 (cvss_changed)
Re-analysis Queued
Jun 11, 2026 - 10:22 vuln.today
cvss_changed
Severity Changed
Jun 11, 2026 - 10:22 NVD
MEDIUM HIGH
CVSS changed
Jun 11, 2026 - 10:22 NVD
6.7 (MEDIUM) 7.0 (HIGH)
EUVD ID Assigned
Apr 09, 2026 - 15:30 euvd
EUVD-2026-20910
Analysis Generated
Apr 09, 2026 - 15:30 vuln.today
CVE Published
Apr 09, 2026 - 14:49 nvd
MEDIUM 6.7

DescriptionNVD

A flaw was found in libcap. A local unprivileged user can exploit a Time-of-check-to-time-of-use (TOCTOU) race condition in the cap_set_file() function. This allows an attacker with write access to a parent directory to redirect file capability updates to an attacker-controlled file. By doing so, capabilities can be injected into or stripped from unintended executables, leading to privilege escalation.

AnalysisAI

Local privilege escalation in libcap's cap_set_file() function affects Red Hat Enterprise Linux 6 through 10 and OpenShift Container Platform 4, where a TOCTOU race condition allows an unprivileged user with write access to a parent directory to redirect file capability updates onto an attacker-controlled file. Successful exploitation can inject or strip Linux file capabilities on arbitrary executables, yielding full privilege escalation on the host. No public exploit identified at time of analysis and EPSS is 0.01%, but a vendor patch is available.

Technical ContextAI

libcap is the userspace library implementing the POSIX.1e capability model on Linux, providing the setcap/getcap utilities and the cap_set_file() API that wraps the underlying setxattr() syscall on the security.capability extended attribute. The flaw is a classic CWE-367 Time-of-Check Time-of-Use race: cap_set_file() resolves and validates a path before performing the capability write, so between those two steps an attacker who controls the containing directory can swap the target (for example via rename or symlink manipulation) so the privileged xattr is applied to a file the attacker chose rather than the one validated. Because Linux file capabilities are honored on execve() and can grant powers such as CAP_SETUID, CAP_DAC_OVERRIDE, or CAP_SYS_ADMIN, redirecting that write to an attacker-controlled SUID-like target produces full local privilege escalation. The affected products per CPE are Red Hat Enterprise Linux 6, 7, 8, 9, and 10 and Red Hat OpenShift Container Platform 4, all of which ship libcap as a core dependency.

RemediationAI

Patch available per vendor advisory: update libcap to the fixed package versions distributed in RHSA-2026:7473 (and the follow-on errata RHSA-2026:12423, RHSA-2026:12441, RHSA-2026:13285) for Red Hat Enterprise Linux 6/7/8/9/10 and OpenShift Container Platform 4, and to the equivalents in SUSE-SU-2026:1432 / SUSE-SU-2026:1433 for SUSE; on RHEL run 'dnf update libcap' and reboot or restart services that link against it. Until patched, the most effective compensating control is to ensure no unprivileged user has write access to any parent directory of a path that root or another capability-bearing process passes to setcap/cap_set_file() - audit build pipelines, container image builders, and shared scratch directories for directories writable by untrusted users that contain executables ever subjected to setcap, and relocate setcap operations into root-owned, mode 0755 directories. Where feasible, avoid running setcap on files in user-writable trees and prefer baking capabilities into immutable images; note that disabling file capabilities entirely is rarely practical because many distro packages rely on them (ping, etc.).

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Vendor StatusVendor

SUSE

Severity: Medium
Product Status
Container private-registry/harbor-core:1.1.2-2.22 Container private-registry/harbor-exporter:1.1.2-2.22 Container private-registry/harbor-jobservice:1.1.2-2.22 Container private-registry/harbor-portal:1.1.2-2.23 Container private-registry/harbor-registry:1.1.2-2.22 Container private-registry/harbor-registryctl:1.1.2-2.22 Container private-registry/harbor-trivy-adapter:1.1.2-2.25 Container suse/manager/4.3/proxy-httpd:4.3.17.9.76.10 Container suse/manager/4.3/proxy-salt-broker:4.3.17.9.66.11 Container suse/manager/4.3/proxy-squid:4.3.17.9.75.8 Container suse/manager/4.3/proxy-ssh:4.3.17.9.66.8 Container suse/manager/4.3/proxy-tftpd:4.3.17.9.66.9 Container suse/sle-micro/base-5.5:2.0.4-5.8.263 Container suse/sle-micro/kvm-5.5:2.0.4-3.5.507 Affected
Container suse/ltss/sle12.5/sles12sp5:8.5.225 Affected
Container suse/sl-micro/6.0/baremetal-os-container:2.1.3-6.163 Container suse/sl-micro/6.0/base-os-container:2.1.3-7.130 Container suse/sl-micro/6.0/kvm-os-container:2.1.3-6.147 Affected
Container suse/sl-micro/6.0/toolbox:13.2-9.96 Affected
SUSE Linux Enterprise Desktop 15 SP7 SUSE Linux Enterprise High Performance Computing 15 SP7 SUSE Linux Enterprise Module for Basesystem 15 SP7 SUSE Linux Enterprise Server 15 SP7 SUSE Linux Enterprise Server for SAP Applications 15 SP7 Fixed

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CVE-2026-4878 vulnerability details – vuln.today

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