Quick answers
- Is CVE-2026-123876 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-123876 being exploited in the wild.
- How severe is CVE-2026-123876?
- Medium severity, with a CVSS score of 4.4, published 6 November 2026.
- Which products and versions are affected?
- RedHat containers-common.
- Is there a fix for CVE-2026-123876?
- No fixed version is recorded yet. Enforce SELinux policy as an additional control, as it may still deny vsock access even with the unfixed seccomp profile. Deploy updated seccomp profiles that use SCMP_CMP_MASKED_EQ for proper 32-bit masking of socket arguments. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-123876 attacked?
- It is attacked with local access, in a software library.
- Am I affected by CVE-2026-123876?
- Check whether you run Redhat Containers-Common. 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.
How to fix
Enforce SELinux policy as an additional control, as it may still deny vsock access even with the unfixed seccomp profile. Deploy updated seccomp profiles that use SCMP_CMP_MASKED_EQ for proper 32-bit masking of socket arguments.
Technical details
The default seccomp profile in containers-common uses unmasked 64-bit equality comparisons for AF_VSOCK and NETLINK_AUDIT deny rules, but the kernel truncates these socket arguments to 32 bits. An attacker can set the upper 32 bits to bypass the deny rules. This is an access control bypass (CWE-184) requiring local or container-level privileges with no user interaction needed. A fix exists via SCMP_CMP_MASKED_EQ profile updates.
Affected products
- RedHat containers-common
Timeline
- 2026-11-06: disclosed