Skip to content
Fencer Vulns
high 7.8

CVE-2026-74257 json

sockmap: Fix use-after-free in udp_bpf_recvmsg()

published 2026-08-15 2 mo ago modified 2026-10-30 10 d ago also EUVD-2026-59404

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

In the Linux kernel, the following vulnerability has been resolved:

sockmap: Fix use-after-free in udp_bpf_recvmsg()

syzbot reported use-after-free of struct sk_msg in sk_msg_recvmsg(). [0]

sk_msg_recvmsg() peeks sk_msg from psock->ingress_msg under a lock, but its processing is lockless.

Thus, sk_msg_recvmsg() must be serialised by callers, otherwise multiple threads could touch the same sk_msg.

For example, TCP uses lock_sock(), and AF_UNIX uses unix_sk(sk)->iolock.

Initially, udp_bpf_recvmsg() had used lock_sock(), but the cited commit removed it.

Let's serialise sk_msg_recvmsg() with lock_sock() in udp_bpf_recvmsg().

Note that holding spin_lock_bh(&sk->sk_receive_queue.lock) is not an option due to copy_page_to_iter() in sk_msg_recvmsg().

[0]: BUG: KASAN: slab-use-after-free in sk_msg_recvmsg+0xb54/0xc30 net/core/skmsg.c:428 Read of size 4 at addr ffff88814cdcf000 by task syz.0.24/6020

CPU: 1 UID: 0 PID: 6020 Comm: syz.0.24 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026 Call Trace: <TASK> dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0xba/0x230 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 sk_msg_recvmsg+0xb54/0xc30 net/core/skmsg.c:428 udp_bpf_recvmsg+0x4bd/0xe00 net/ipv4/udp_bpf.c:84 inet_recvmsg+0x260/0x270 net/ipv4/af_inet.c:891 sock_recvmsg_nosec net/socket.c:1078 [inline] sock_recvmsg+0x1a8/0x270 net/socket.c:1100 ____sys_recvmsg+0x1e6/0x4a0 net/socket.c:2812 ___sys_recvmsg+0x215/0x590 net/socket.c:2854 do_recvmmsg+0x334/0x800 net/socket.c:2949 __sys_recvmmsg net/socket.c:3023 [inline] __do_sys_recvmmsg net/socket.c:3046 [inline] __se_sys_recvmmsg net/socket.c:3039 [inline] __x64_sys_recvmmsg+0x198/0x250 net/socket.c:3039 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb319f9aeb9 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fb31ad97028 EFLAGS: 00000246 ORIG_RAX: 000000000000012b RAX: ffffffffffffffda RBX: 00007fb31a216090 RCX: 00007fb319f9aeb9 RDX: 0000000000000001 RSI: 0000200000000400 RDI: 0000000000000004 RBP: 00007fb31a008c1f R08: 0000000000000000 R09: 0000000000000000 R10: 0000000040000021 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fb31a216128 R14: 00007fb31a216090 R15: 00007ffe21dd0a98 </TASK>

Allocated by task 6019: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x3d1/0x6e0 mm/slub.c:5780 kmalloc_noprof include/linux/slab.h:957 [inline] kzalloc_noprof include/linux/slab.h:1094 [inline] alloc_sk_msg net/core/skmsg.c:510 [inline] sk_psock_skb_ingress_self+0x60/0x350 net/core/skmsg.c:612 sk_psock_verdict_apply net/core/skmsg.c:1038 [inline] sk_psock_verdict_recv+0x7d9/0x8d0 net/core/skmsg.c:1236 udp_read_skb+0x73e/0x7e0 net/ipv4/udp.c:2045 sk_psock_verdict_data_ready+0x12d/0x550 net/core/skmsg.c:1257 __udp_enqueue_schedule_skb+0xc54/0x10b0 net/ipv4/udp.c:1789 __udp_queue_rcv_skb net/ipv4/udp.c:2346 [inline] udp_queue_rcv_one_skb+0xac5/0x19c0 net/ipv4/udp.c:2475 __udp4_lib_mcast_deliver+0xc06/0xcf0 net/ipv4/udp.c:2585 __udp4_lib_rcv+0x10f6/0x2620 net/ipv4/udp.c:2724 ip_protocol_deliver_rcu+0x282/0x440 net/ipv4/ip_input.c:207 ip_local_deliver_finish+0x3bb/0x6f0 net/ipv4/ip_input.c:241 NF_HOOK+0x336/0x3c0 include/linux/netfilter.h:318 dst_input include/net/dst.h:474 [inline] ip_sublist_rcv_finish+0x221/0x2a0 net/ipv4/ip_input.c:584 ip_list_rcv_finish net/ipv4/ip_inp ---truncated---

Patch / fix

  • Linux Linux 6.1.191, 6.6.160, 6.12.114, 6.18.40, 7.1.5, 7.2
  • linux Debian 13 6.12.115-2
  • linux Debian 14 7.1.5-1

debian advisories DEBIAN-CVE-2026-74257

  • linux Ubuntu 26.04 LTS 7.0.0-38.38
  • linux-aws Ubuntu 26.04 LTS 7.0.0-1014.14
  • linux-gcp Ubuntu 26.04 LTS 7.0.0-1014.14
  • linux-gke Ubuntu 26.04 LTS 7.0.0-1008.9
  • linux-ibm Ubuntu 26.04 LTS 7.0.0-1015.15
  • linux-azure Ubuntu 26.04 LTS 7.0.0-1017.17
  • linux-riscv Ubuntu 26.04 LTS 7.0.0-38.38.1
  • linux-oracle Ubuntu 26.04 LTS 7.0.0-1013.13

ubuntu advisories UBUNTU-CVE-2026-74257

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.84.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.84.1
  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.84.1
  • kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.84.1
  • kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.84.1
  • kernel-zfcpdump SLE Module for Basesystem 15 SP7 6.4.0-150700.53.84.1
  • kernel-obs-build SLE Module for Development Tools 15 SP7 6.4.0-150700.53.84.1
  • kernel-default-base SLE Module for Basesystem 15 SP7 6.4.0-150700.53.84.1.150700.17.47.1

suse advisories SUSE-SU-2026:4706-1SUSE-SU-2026:4640-1SUSE-SU-2026:24316-1SUSE-SU-2026:24315-1SUSE-SU-2026:24181-1SUSE-SU-2026:24182-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.39.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.39.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.39.1

opensuse advisories openSUSE-SU-2026:22091-1

  • kernel Azure Linux 3.0 6.6.161.1-1

azure linux advisories AZL-96573

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-74257 updated cvss 5.5

kernel: sockmap: Fix use-after-free in udp_bpf_recvmsg()

  • Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    affected: no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
23 d ago

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.