In the Linux kernel, the following vulnerability has been resolved:
mptcp: fix slab-use-after-free in __inet_lookup_established
The ehash table lookups are lockless and rely on
SLAB_TYPESAFE_BY_RCU to guarantee socket memory stability
during RCU read-side critical sections. Both tcp_prot and
tcpv6_prot have their slab caches created with this flag
via proto_register().
However, MPTCP's mptcp_subflow_init() copies tcpv6_prot into
tcpv6_prot_override during inet_init() (fs_initcall, level 5),
before inet6_init() (module_init/device_initcall, level 6) has
called proto_register(&tcpv6_prot). At that point,
tcpv6_prot.slab is still NULL, so tcpv6_prot_override.slab
remains NULL permanently.
This causes MPTCP v6 subflow child sockets to be allocated via
kmalloc (falling into kmalloc-4k) instead of the TCPv6 slab
cache. The kmalloc-4k cache lacks SLAB_TYPESAFE_BY_RCU, so
when these sockets are freed without SOCK_RCU_FREE (which is
cleared for child sockets by design), the memory can be
immediately reused. Concurrent ehash lookups under
rcu_read_lock can then access freed memory, triggering a
slab-use-after-free in __inet_lookup_established.
Fix this by splitting the IPv6-specific initialization out of
mptcp_subflow_init() into a new mptcp_subflow_v6_init(), called
from mptcp_proto_v6_init() before protocol registration. This
ensures tcpv6_prot_override.slab correctly inherits the
SLAB_TYPESAFE_BY_RCU slab cache.
References
Configurations
Configuration 1 (hide)
|
History
27 Apr 2026, 20:09
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://git.kernel.org/stable/c/15fa9ead4d5e6b6b9c794e84144146c917f2cb62 - Patch | |
| References | () https://git.kernel.org/stable/c/3fd6547f5b8ac99687be6d937a0321efda760597 - Patch | |
| References | () https://git.kernel.org/stable/c/9b55b253907e7431210483519c5ad711a37dafa1 - Patch | |
| References | () https://git.kernel.org/stable/c/b313e9037d98c13938740e5ebda7852929366dff - Patch | |
| References | () https://git.kernel.org/stable/c/eb9c6aeb512f877cf397deb1e4526f646c70e4a7 - Patch | |
| References | () https://git.kernel.org/stable/c/f6e1f25fa5e733570f6d6fe37a4dfed2a0deba47 - Patch | |
| References | () https://git.kernel.org/stable/c/fb1f54b7d16f393b8b65d328410f78b4beea8fcc - Patch | |
| CWE | CWE-416 | |
| First Time |
Linux
Linux linux Kernel |
|
| CPE | cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.12:-:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:* |
27 Apr 2026, 15:16
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 9.8 |
24 Apr 2026, 15:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-04-24 15:16
Updated : 2026-04-27 20:09
NVD link : CVE-2026-31669
Mitre link : CVE-2026-31669
CVE.ORG link : CVE-2026-31669
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-416
Use After Free