---
id: CVE-2026-74256
title: "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, sockmap: fix integer overflow in bpf_msg_pop_data() bounds check\n\nstart and len are u32, so\n\n\tu64 last = start + len;\n\nevaluates start + len in 32-bit and wraps be…"
summary: "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf, sockmap: fix integer overflow in bpf_msg_pop_data() bounds check\n\nstart and len are u32, so\n\n\tu64 last = start + len;\n\nevaluates start + len in 32-bit and wraps be…"
severity: high
cvss: 8.4
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-476
vendor: Red Hat
product: Red Hat Enterprise Linux 9
affected:
  - enterprise_linux 10
  - enterprise_linux 6
  - enterprise_linux 8
  - enterprise_linux 9
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T19:17:34.317'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-74256'
references:
  - url: 'https://git.kernel.org/stable/c/17eb9832a10db2f7a80cb429ca2bc5038445a943'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9ef44ed6fb0c1db01cfcc3de432a33e719713eb5'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a48802fb2cd2d1e23651989f8ff4d15e9d5dad54'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/ba5cc05dae8fce237d191c7ea96b1107a791e548'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/c05a0ec1cdced622a1a0c7d85679fe02f31033ec'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d693c5ed67dabe1ccbf8dcea93075bdc9ffd4ca0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/e09f7bd7273928b4089e6b71f8e992f2b356ca1b'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fe09dd288722f1c749b7506c0b3e7841a7d85027'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74256.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-74256'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2516834'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-74256'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-74256'
  - url: 'https://kernelcve.org/list/?q=CVE-2026-74256'
  - url: >-
      https://lore.kernel.org/linux-cve-announce/2026081541-CVE-2026-74256-a6a4@gregkh/T
tags:
  - nvd
  - csaf
  - vex
  - red-hat
  - cve.org
  - score-dispute
epss: 0.00185
epssPercentile: 0.08013
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-10-16T18:51:25.562795Z'
scores:
  nvd: 8.4
  vendor: 5.5
  cna: 8.4
ingestedAt: '2026-10-16T19:46:24.388Z'
---

## Overview

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

bpf, sockmap: fix integer overflow in bpf_msg_pop_data() bounds check

start and len are u32, so

	u64 last = start + len;

evaluates start + len in 32-bit and wraps before storing it in last.
The bounds check

	if (start >= offset + l || last > msg->sg.size)
		return -EINVAL;

can then be passed with an out-of-range start/len, after which the pop
loop runs off the end of the scatterlist and sk_msg_shift_left() calls
put_page() on the empty msg->sg.end slot:

  Oops: general protection fault, probably for non-canonical address
  0xdffffc0000000001: 0000 [#1] SMP KASAN PTI
  KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
  RIP: 0010:sk_msg_shift_left net/core/filter.c:2957 [inline]
  RIP: 0010:____bpf_msg_pop_data net/core/filter.c:3103 [inline]
  RIP: 0010:bpf_msg_pop_data+0x753/0x1a10 net/core/filter.c:2984
  Call Trace:
   <TASK>
   bpf_prog_4cc92c278f4d5d56+0x1b1/0x1e8
   bpf_prog_run_pin_on_cpu+0x107/0x320 include/linux/filter.h:746
   sk_psock_msg_verdict+0x357/0x7f0 net/core/skmsg.c:934
   tcp_bpf_send_verdict net/ipv4/tcp_bpf.c:420 [inline]
   tcp_bpf_sendmsg+0x766/0x1ae0 net/ipv4/tcp_bpf.c:583
   __sock_sendmsg+0x153/0x1c0 net/socket.c:802
   __sys_sendto+0x326/0x430 net/socket.c:2265
   __x64_sys_sendto+0xe3/0x100 net/socket.c:2268
   do_syscall_64+0x14c/0x480
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
   </TASK>

Widen the addition with a (u64) cast so the bound is evaluated in
64-bit and a len near U32_MAX no longer wraps below msg->sg.size.

While here, change pop from int to u32. It counts bytes against the
unsigned scatterlist lengths and can never be negative, so the signed
type only invites sign-confusion in the pop loop.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · no fix planned: Red Hat Enterprise Linux 6, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9 · updated 2026-10-26 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74256.json)