CVE-2017-5551: The simple_set_acl function in fs/posix_acl.c in the Linux kernel before 4.9.6 preserves the setgid bit dur...

Security readout for executives and security teams

CVE-2017-5551 is a Linux kernel local privilege issue. On affected kernels before 4.9.6, a local user may be able to gain unintended group privileges through tmpfs ACL handling when a setgid program with restricted execute permissions exists. Exposure is most relevant on Linux systems running kernels before 4.9.6 or vendor kernels without the backported fix, especially multi-user systems, shared hosting, build hosts, or container hosts where untrusted local users can interact with tmpfs-backed filesystems. Treat this as a patch-priority issue for shared Linux environments, not an internet-edge emergency. It needs timely remediation where local users or workloads are not fully trusted, but the provided sources do not show remote exploitation or active exploitation. Mitigation focus: Update to Linux kernel 4.9.6 or a vendor-supported backport containing the fix.; Review Debian DSA-3791, Red Hat Bugzilla, and distribution advisories for package-specific remediation.; Prioritize shared systems where untrusted users have local shell, build, or container access..

Prepared

Jun 13, 2026, 06:20 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.