Sidero Labs Talos Linux privilege escalation via Linux kernel page cache corruption

Severity: high · CVSS 7.5 · Published 2026-05-07

A vulnerability in the underlying Linux kernel allows an attacker with basic access to a Kubernetes cluster to take full control of the host server. By deploying a standard container, an attacker can corrupt shared system files used by high-privilege background services, leading to unauthorized code execution as a root user. This could result in the theft of sensitive node secrets, access to the host filesystem, and a complete compromise of the affected infrastructure.

Technologies: github.com/siderolabs/talos (Go). Vendors: Go, Sidero Labs.

Quick answers

Is This vulnerability exploited in the wild?
No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
How severe is This vulnerability?
High severity, with a CVSS score of 7.5, published 7 May 2026.
Which products and versions are affected?
github.com/siderolabs/talos (Go) < 1.12.7; Sidero Labs Talos Linux < 1.12.7, < 1.13.0.
Is there a fix for This vulnerability?
A patch was published on 2026-05-07: Fixes available in Talos v1.12.7 and v1.13.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is This vulnerability attacked?
It is attacked with local access, in an operating system.
Am I affected?
Check whether you run github.com/siderolabs/talos (Go) or Sidero Labs Talos Linux 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 vulnerability in the Linux kernel's algif_aead subsystem (CVE-2026-31431, known as 'copy.fail') allows an unprivileged user to corrupt arbitrary file page-cache pages using the AF_ALG crypto interface and the splice() system call. In Talos Linux, this can be exploited by a standard Kubernetes pod to poison binaries (such as /usr/sbin/nft) in containerd snapshot layers shared with privileged DaemonSets like kube-proxy. When the privileged service executes the corrupted binary, the attacker gains root-level code execution on the host. The issue is resolved in Talos v1.13.0 and v1.12.7 by updating to Linux kernel 6.18.25, which includes the necessary revert of in-place optimization in algif_aead.

Affected products

  • Sidero Labs Talos Linux < 1.12.7, < 1.13.0

Timeline

  • 2026-05-01: disclosed: Initial advisory publication by Sidero Labs
  • 2026-05-07: advisory: GitHub Advisory published
  • 2026-05-07: patched: Fixes available in Talos v1.12.7 and v1.13.0

References

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