CVE-2026-64551: Critical vulnerability in Linux kernel

Introduction

The CVE-2026-64551 vulnerability affects the Linux kernel and allows reading uninitialized memory, which can compromise system security.

What happened?

When an ERROR chunk with a STALE_COOKIE cause is received in the COOKIE_ECHOED state, the function sctp_sf_do_5_2_6_stale() reads a 4-byte field that follows the cause header. This field, called Measure of Staleness, may not be present, leading to reading beyond the expected range and resulting in exposure of uninitialized memory to the peer.

How the vulnerability works

The vulnerability lies in how the Linux kernel handles ERROR chunks in the SCTP protocol. The function that processes these chunks does not adequately validate the length of the STALE_COOKIE cause before attempting to read the staleness field. This can allow an attacker, who can manipulate an association into the COOKIE_ECHOED state, to access sensitive data that should not be exposed.

What is the real impact?

The impact of this vulnerability is classified as critical, as it allows reading uninitialized memory, potentially exposing sensitive information. Any peer that can induce an association into the COOKIE_ECHOED state can exploit this flaw, including unprivileged processes using raw SCTP sockets.

Which versions are affected?

• linux kernel ≥ 2.6.12.1 < 5.10.261
• linux kernel ≥ 5.11 < 5.15.212
• linux kernel ≥ 5.16 < 6.1.178
• linux kernel ≥ 6.2 < 6.6.145
• linux kernel ≥ 6.7 < 6.12.97
• linux kernel ≥ 6.13 < 6.18.40
• linux kernel ≥ 6.19 < 7.1.5
• linux kernel 2.6.12

How to fix

1. Check your Linux kernel version.
2. Upgrade to a patched version of the kernel as indicated by the vendor.
3. Consider applying available security patches.
4. Regularly monitor kernel updates to ensure you are always protected.

Mitigation while you update

While an update is not possible, it is recommended to limit network access and restrict the use of SCTP sockets to trusted processes. Additionally, consider implementing firewalls and other security measures to mitigate potential exploits.

Conclusion

The CVE-2026-64551 vulnerability in the Linux kernel poses a significant security risk. It is crucial for system administrators and server owners to take immediate action to address or mitigate this flaw.