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

Source: https://junglewise.ai/threats/sidero-labs-talos-linux-privilege-escalation-via-linux-kernel-page-91566f1b  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-07. Updated: 2026-06-09  
License: CC BY 4.0 with a link back

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)](https://junglewise.ai/threats/technologies/github-com-siderolabs-talos). Vendors: [Go](https://junglewise.ai/threats/vendors/go), [Sidero Labs](https://junglewise.ai/threats/vendors/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

- [https://github.com/siderolabs/talos/security/advisories/GHSA-m38g-vww2-mvgx](https://github.com/siderolabs/talos/security/advisories/GHSA-m38g-vww2-mvgx)
- [https://github.com/Percivalll/Copy-Fail-CVE-2026-31431-Kubernetes-PoC](https://github.com/Percivalll/Copy-Fail-CVE-2026-31431-Kubernetes-PoC)
- [https://github.com/theori-io/copy-fail-CVE-2026-31431](https://github.com/theori-io/copy-fail-CVE-2026-31431)
- [https://xint.io/blog/copy-fail-linux-distributions](https://xint.io/blog/copy-fail-linux-distributions)
- [https://api.github.com/repos/siderolabs/talos/security-advisories/GHSA-m38g-vww2-mvgx](https://api.github.com/repos/siderolabs/talos/security-advisories/GHSA-m38g-vww2-mvgx)

## Related threats

- [Talos Linux ships runc vulnerable to the escape to the host attack](https://junglewise.ai/threats/talos-linux-ships-runc-vulnerable-to-the-escape-to-the-host-attack-54b884df)
- [nftables binding to an already bound chain](https://junglewise.ai/threats/nftables-binding-to-an-already-bound-chain-2fa7c649)