Publicly disclosed April 29, 2026, CVE-2026-31431 affects the algif_aead kernel module present in all mainstream Linux distributions running kernels built since 2017, including Ubuntu 24.04 LTS, Amazon Linux 2023, RHEL 10.1, and SUSE 16. The upstream fix was committed April 1 but had not been packaged by any major distro at time of disclosure, leaving a gap between fix availability and deployable remediation. The vulnerability exploits the AF_ALG socket interface to perform a targeted 4-byte write to page-cache memory, sufficient to gain root privileges from an unprivileged local user session. The absence of vendor kernel packages at disclosure time makes this unusually dangerous for cloud and container workloads — Kubernetes nodes and CI/CD runners are considered highest priority. Recommended mitigations while awaiting patches include disabling the algif_aead module via modprobe blacklist and applying seccomp policies to block AF_ALG socket creation in container environments. Organizations running self-managed Linux infrastructure should treat this as an urgent operational item until distro packages land.