CVE-2025-38181

A flaw was found in the Linux kernel's CALIPSO (Common Architecture for Label Internet Security Protocols) component. A local attacker with low privileges could exploit a null pointer dereference vulnerability in the calipso_req_setattr() and calipso_req_delattr() functions. This occurs when the kernel attempts to allocate a CALIPSO option while handling SYN cookies, potentially leading to a system crash and a denial of service (DoS).

A flaw of Moderate impact was found in the Linux kernel CALIPSO (Common Architecture for Label Internet Security Protocols) implementation, which is used by NetLabel/SELinux to apply security labels to IPv6 traffic. When a listening IPv6 socket is subject to a SYN flood and the kernel replies with SYN cookies, the request socket's listener pointer can be NULL; calipso_req_setattr() and calipso_req_delattr() then dereference that NULL pointer while allocating or removing a CALIPSO option for the connection request, crashing the kernel and causing a denial of service. Only the availability of the system is affected; confidentiality and integrity are not. Red Hat rates this flaw as Moderate with a CVSS 3.1 score of 5.5 (AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H), reflecting a local attack vector that requires low privileges, whereas the CVE.org record assigns a network-vector score of 7.5. Red Hat Enterprise Linux 6 and 7 are not affected because the vulnerable code is not present in those streams. The kernel and kernel-rt packages in Red Hat Enterprise Linux 8, 9, and 10, and the kernel in Red Hat In-Vehicle OS 1, are affected, and fixes are currently deferred because the issue is limited to a denial of service in the CALIPSO SYN cookie path and primarily exposes systems that are configured to use CALIPSO IPv6 network labeling. The residual risk of deferral is a kernel crash and resulting system outage on systems where CALIPSO labeling is in use and SYN cookies are triggered.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.