OSG-SEC-2026-07-06 HIGH Linux Kernel epoll Local Privilege Escalation (CVE-2026-46242)

Linux Kernel epoll Local Privilege Escalation (CVE-2026-46242)

Dear OSG Security Contacts,

A Linux kernel vulnerability has been identified in the eventpoll (epoll) subsystem (CVE-2026-46242). The vulnerability results from a race condition that may allow an unprivileged local user to trigger kernel memory corruption and potentially obtain elevated privileges or execute arbitrary code on affected systems. Since epoll is a core Linux kernel component used by many applications and services, a broad range of Linux systems may be affected.

WHAT ARE THE VULNERABILITIES:

The flaw is caused by a race condition in the kernel's event notification handling that can result in a use-after-free memory error. If successfully triggered, the vulnerability allows an attacker to manipulate kernel memory after it has been released, creating an opportunity to crash the system or potentially escalate privileges through kernel memory corruption.
Although there are currently no reports of active exploitation, a public proof-of-concept exploit has been released, increasing the likelihood of future exploitation. Organizations should apply vendor-provided kernel updates as they become available.

IMPACTED VERSIONS:

The vulnerability affects Linux systems running kernel versions that include the vulnerable epoll code.
The following Red Hat Enterprise Linux releases are affected:
- Red Hat Enterprise Linux 9
- Red Hat Enterprise Linux 10

Ubuntu, Debian, SUSE, Fedora, and other Linux distributions may also be affected depending on the kernel package version and vendor backports.
Administrators should monitor their Linux distribution vendor for kernel updates addressing this vulnerability.

WHAT YOU SHOULD DO:

Apply vendor-provided kernel updates addressing CVE-2026-46242 when they become available. A system reboot is required after installing the updated kernel for the changes to take effect.
Restrict or monitor access from untrusted users on affected systems.
There is currently no practical mitigation that fully eliminates exposure prior to patching because the vulnerability resides within the core of the Linux kernel.
Continue to monitor your Linux distribution vendor for additional security advisories and updated kernel packages.

REFERENCES

[1] https://nvd.nist.gov/vuln/detail/CVE-2026-46242
[2] https://www.cve.org/CVERecord?id=CVE-2026-46242
[3] https://github.com/J-jaeyoung/bad-epoll
[4] https://access.redhat.com/security/cve/cve-2026-46242
[5] https://security-tracker.debian.org/tracker/CVE-2026-46242
[6] https://almalinux.org/ja/blog/2026-07-06-januscape-bad-epoll/
[7] https://threat-modeling.com/cve-2026-46242-bad-epoll-linux-kernel-root-privesc-android/

Please contact the OSG security team at [email protected] if you have any questions or concerns.

OSG Security Team