sctp: linearize cloned gso packets in sctp_rcv
CVE: CVE-2025-38718
Component: kernel
CWE: CWE-664
Severity: Moderate
CVSS v3: 7.5/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Release date: 2025-09-04T00:00:00+00:00

A flaw use of uninitialized memory (uncontrolled and invisible by attacker) in the Linux kernel SCTP transport protocol was found in the way user triggers malicious SCTP packets. A remote user could use this flaw to crash the system. The bug actual only for systems where SCTP protocol being enabled and used.

Statement: A flaw in the SCTP receive path failed to linearize cloned GSO sk_buffs before accessing fraglists, leading to reads of uninitialized memory as reported by KMSAN. An attacker sending SCTP traffic can trigger incorrect processing and potentially cause a kernel denial of service on the target under specific RX conditions.
Stream Control Transmission Protocol (SCTP) is a transport-layer protocol (like TCP or UDP) primarily used in telecom signaling and some specialized applications. On most Linux systems it is disabled by default, and remote connectivity is only possible if SCTP support is enabled and listening services are configured (commonly using the IANA-assigned port 2905/tcp for M3UA or other protocol-specific ports). Therefore, the vulnerability is only exploitable when SCTP is enabled and reachable on the target system.
Although KMSAN reports this issue as use of uninitialized memory (which deterministically crashes with KMSAN enabled), on production kernels the impact is still availability-related.

Remediation:
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

The system must be rebooted for this update to take effect.
To mitigate this issue, prevent module sctp from being loaded. Please see https://access.redhat.com/solutions/41278 for how to blacklist a kernel module to prevent it from loading automatically.