Is CVE-2026-4878 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-4878 being exploited in the wild.

How severe is CVE-2026-4878?

Medium severity, with a CVSS score of 6.7, published 9 April 2026.

Is there a fix for CVE-2026-4878?

A patch was published on 2026-04-30: Red Hat released security updates for RHEL 9 and 10 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-4878 attacked?

It is attacked with local access, in a software library.

Am I affected by CVE-2026-4878?

Check whether you run Libcap Project Libcap at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-4878: libcap privilege escalation via TOCTOU race condition in cap_set_file

CVE-2026-4878 · Severity: medium · CVSS 6.7 · Published 2026-04-09

A security vulnerability has been identified in libcap, a standard Linux library used to manage fine-grained system permissions (capabilities). A local attacker can exploit a timing flaw to trick the system into granting administrative-level permissions to unauthorized files. This could allow a standard user to gain full control over the system or disrupt critical security protections.

Quick answers

Is CVE-2026-4878 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-4878 being exploited in the wild.
How severe is CVE-2026-4878?: Medium severity, with a CVSS score of 6.7, published 9 April 2026.
Which products and versions are affected?: Libcap Project Libcap -.
Is there a fix for CVE-2026-4878?: A patch was published on 2026-04-30: Red Hat released security updates for RHEL 9 and 10 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-4878 attacked?: It is attacked with local access, in a software library.
Am I affected by CVE-2026-4878?: Check whether you run Libcap Project Libcap at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A Time-of-check-to-time-of-use (TOCTOU) race condition exists in the cap_set_file() function within libcap. A local unprivileged attacker with write access to a parent directory can exploit this race to redirect file capability updates to an attacker-controlled file. By manipulating the file system during the window between the library's check and the actual application of capabilities, an attacker can inject capabilities into unauthorized executables or strip them from legitimate ones. This leads to local privilege escalation. Red Hat has released security updates (e.g., RHSA-2026:12423, RHSA-2026:12441) to address this issue across various Enterprise Linux versions.

Affected products

libcap project libcap -
Red Hat Enterprise Linux 8.0
Red Hat Enterprise Linux 9.0
Red Hat Enterprise Linux 10.0
Red Hat Openshift Container Platform 4.0

Timeline

2026-04-07: disclosed: Initial disclosure on oss-security mailing list
2026-04-09: advisory: CVE-2026-4878 published
2026-04-30: patched: Red Hat released security updates for RHEL 9 and 10

References

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