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Fencer Vulns
high 7.1

CVE-2026-45856 json

RDMA/uverbs: Validate wqe_size before using it in ib_uverbs_post_send

published 2026-05-27 5 mo ago modified 2026-10-19 20 d ago also EUVD-2026-32322

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 8%
public exploits
0
none known

Summary

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

RDMA/uverbs: Validate wqe_size before using it in ib_uverbs_post_send

ib_uverbs_post_send() uses cmd.wqe_size from userspace without any validation before passing it to kmalloc() and using the allocated buffer as struct ib_uverbs_send_wr.

If a user provides a small wqe_size value (e.g., 1), kmalloc() will succeed, but subsequent accesses to user_wr->opcode, user_wr->num_sge, and other fields will read beyond the allocated buffer, resulting in an out-of-bounds read from kernel heap memory. This could potentially leak sensitive kernel information to userspace.

Additionally, providing an excessively large wqe_size can trigger a WARNING in the memory allocation path, as reported by syzkaller.

This is inconsistent with ib_uverbs_unmarshall_recv() which properly validates that wqe_size >= sizeof(struct ib_uverbs_recv_wr) before proceeding.

Add the same validation for ib_uverbs_post_send() to ensure wqe_size is at least sizeof(struct ib_uverbs_send_wr).

Patch / fix

  • Linux Linux 5.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.14, 6.19.4, 7.0
  • linux Debian 12 6.1.170-1
  • linux Debian 13 6.12.85-1
  • linux Debian 14 6.18.14-1

debian advisories DEBIAN-CVE-2026-45856

  • linux Ubuntu 22.04 LTS 5.15.0-186.196
  • linux Ubuntu 24.04 LTS 6.8.0-134.134
  • linux-aws Ubuntu 22.04 LTS 5.15.0-1112.119
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1060.63
  • linux-gcp Ubuntu 22.04 LTS 5.15.0-1112.122
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1063.69
  • linux-gke Ubuntu 22.04 LTS 5.15.0-1108.114
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1058.64

ubuntu advisories UBUNTU-CVE-2026-45856

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 RHEL 8 4.18.0-553.171.1.el8_10
  • perf RHEL 8 4.18.0-553.171.1.el8_10
  • bpftool RHEL 8 4.18.0-553.171.1.el8_10
  • kernel-core RHEL 8 4.18.0-553.171.1.el8_10
  • kernel-tools RHEL 8 4.18.0-553.171.1.el8_10
  • python3-perf RHEL 8 4.18.0-553.171.1.el8_10
  • kernel-modules RHEL 8 4.18.0-553.171.1.el8_10
  • kernel-zfcpdump RHEL 8 4.18.0-553.171.1.el8_10

red hat advisories RHSA-2026:75747RHSA-2026:75746RHSA-2026:74438

  • kernel-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-48.1
  • kernel-source-rt Linux Micro 6.1, Linux Micro 6.0 6.4.0-48.1
  • kernel-rt Real Time Module 15 SP7 6.4.0-150700.7.59.2
  • kernel-syms-rt Real Time Module 15 SP7 6.4.0-150700.7.59.1
  • kernel-source-rt Real Time Module 15 SP7 6.4.0-150700.7.59.2
  • kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.60.1
  • kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.60.1
  • kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.60.1

suse advisories SUSE-SU-2026:22433-1SUSE-SU-2026:22458-1SUSE-SU-2026:2591-1SUSE-SU-2026:2482-1SUSE-SU-2026:22108-1SUSE-SU-2026:22137-1

  • kernel-rt openSUSE Leap 16.0 6.12.0-160000.35.1
  • dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.35.1
  • kernel-64kb openSUSE Leap 16.0 6.12.0-160000.35.1
  • kernel-syms openSUSE Leap 16.0 6.12.0-160000.35.1
  • kernel-azure openSUSE Leap 16.0 6.12.0-160000.35.1
  • kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.35.1
  • kernel-source openSUSE Leap 16.0 6.12.0-160000.35.1
  • kernel-default openSUSE Leap 16.0 6.12.0-160000.35.1

opensuse advisories openSUSE-SU-2026:20965-1

  • kernel AlmaLinux 10 6.12.0-211.63.1.el10_2
  • rv AlmaLinux 10 6.12.0-211.63.1.el10_2
  • perf AlmaLinux 10 6.12.0-211.63.1.el10_2
  • rtla AlmaLinux 10 6.12.0-211.63.1.el10_2
  • libperf AlmaLinux 10 6.12.0-211.63.1.el10_2
  • kernel-rt AlmaLinux 10 6.12.0-211.63.1.el10_2
  • kernel-64k AlmaLinux 10 6.12.0-211.63.1.el10_2
  • kernel-core AlmaLinux 10 6.12.0-211.63.1.el10_2

almalinux advisories ALSA-2026:76738ALSA-2026:75746ALSA-2026:75747ALSA-2026:74438

  • kernel-rt Rocky Linux 8 4.18.0-553.171.1.rt7.512.el8_10
  • kernel Rocky Linux 8 4.18.0-553.171.1.el8_10
  • kernel Rocky Linux 9 5.14.0-687.54.1.el9_8

rocky linux advisories RLSA-2026:75746RLSA-2026:75747RLSA-2026:74438

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-2026-45856 updated cvss 4.4

kernel: RDMA/uverbs: Validate wqe_size before using it in ib_uverbs_post_send

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 9 kernel-rt, kernel-rt-kvm, kernel-rt-core, kernel-rt-modules, kernel-rt-debug-kvm, kernel-rt-debug-core, +12 more
    affected: workaround, no fix available
  • Red Hat Enterprise Linux kernel-modules-internal 6.12.0-211.63.1.el10_2
    fixed: vendor fix RHSA-2026:76738
  • Red Hat Enterprise Linux AppStream (v. 9) rv 5.14.0-687.54.1.el9_8, perf 5.14.0-687.54.1.el9_8, rtla 5.14.0-687.54.1.el9_8, python3-perf 5.14.0-687.54.1.el9_8, kernel-devel-matched 5.14.0-687.54.1.el9_8, kernel-64k-devel-matched 5.14.0-687.54.1.el9_8, +7 more
    fixed: vendor fix RHSA-2026:74438
  • Red Hat Enterprise Linux AppStream (v. 10) rv 6.12.0-211.63.1.el10_2, perf 6.12.0-211.63.1.el10_2, rtla 6.12.0-211.63.1.el10_2, python3-perf 6.12.0-211.63.1.el10_2, kernel-devel-matched 6.12.0-211.63.1.el10_2, kernel-64k-devel-matched 6.12.0-211.63.1.el10_2, +7 more
    fixed: vendor fix RHSA-2026:76738
  • Red Hat Enterprise Linux BaseOS (v. 8) perf 4.18.0-553.171.1.el8_10, kernel 4.18.0-553.171.1.el8_10, bpftool 4.18.0-553.171.1.el8_10, kernel-core 4.18.0-553.171.1.el8_10, kernel-tools 4.18.0-553.171.1.el8_10, python3-perf 4.18.0-553.171.1.el8_10, +15 more
    fixed: vendor fix RHSA-2026:75747
  • Red Hat Enterprise Linux BaseOS (v. 9) kernel 5.14.0-687.54.1.el9_8, kernel-64k 5.14.0-687.54.1.el9_8, kernel-core 5.14.0-687.54.1.el9_8, kernel-tools 5.14.0-687.54.1.el9_8, kernel-modules 5.14.0-687.54.1.el9_8, kernel-64k-core 5.14.0-687.54.1.el9_8, +27 more
    fixed: vendor fix RHSA-2026:74438
  • Red Hat Enterprise Linux BaseOS (v. 10) kernel 6.12.0-211.63.1.el10_2, kernel-64k 6.12.0-211.63.1.el10_2, kernel-core 6.12.0-211.63.1.el10_2, kernel-tools 6.12.0-211.63.1.el10_2, kernel-modules 6.12.0-211.63.1.el10_2, kernel-64k-core 6.12.0-211.63.1.el10_2, +28 more
    fixed: vendor fix RHSA-2026:76738
show 10 more
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) libperf 5.14.0-687.54.1.el9_8, kernel-debuginfo-common-s390x 5.14.0-687.54.1.el9_8, kernel-debuginfo-common-x86_64 5.14.0-687.54.1.el9_8, kernel-debuginfo-common-aarch64 5.14.0-687.54.1.el9_8, kernel-debuginfo-common-ppc64le 5.14.0-687.54.1.el9_8
    fixed: vendor fix RHSA-2026:74438
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) libperf 6.12.0-211.63.1.el10_2, kernel-debuginfo-common-s390x 6.12.0-211.63.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.63.1.el10_2, kernel-debuginfo-common-aarch64 6.12.0-211.63.1.el10_2, kernel-debuginfo-common-ppc64le 6.12.0-211.63.1.el10_2
    fixed: vendor fix RHSA-2026:76738
  • Red Hat Enterprise Linux CRB (v. 8) kernel-debuginfo-common-x86_64 4.18.0-553.171.1.el8_10, kernel-debuginfo-common-aarch64 4.18.0-553.171.1.el8_10, kernel-debuginfo-common-ppc64le 4.18.0-553.171.1.el8_10
    fixed: vendor fix RHSA-2026:75747
  • Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal 6.12.0-211.63.1.el10_2, kernel-debuginfo-common-x86_64 6.12.0-211.63.1.el10_2
    fixed: vendor fix RHSA-2026:76738
  • Red Hat Enterprise Linux NFV (v. 8) kernel-rt 4.18.0-553.171.1.rt7.512.el8_10, kernel-rt-kvm 4.18.0-553.171.1.rt7.512.el8_10, kernel-rt-core 4.18.0-553.171.1.rt7.512.el8_10, kernel-rt-modules 4.18.0-553.171.1.rt7.512.el8_10, kernel-rt-debug-kvm 4.18.0-553.171.1.rt7.512.el8_10, kernel-rt-debug-core 4.18.0-553.171.1.rt7.512.el8_10, +4 more
    fixed: vendor fix RHSA-2026:75746
  • Red Hat Enterprise Linux Real Time (v. 9) kernel-rt 5.14.0-687.54.1.el9_8, kernel-rt-64k 5.14.0-687.54.1.el9_8, kernel-rt-core 5.14.0-687.54.1.el9_8, kernel-rt-modules 5.14.0-687.54.1.el9_8, kernel-rt-64k-core 5.14.0-687.54.1.el9_8, kernel-rt-debug-core 5.14.0-687.54.1.el9_8, +14 more
    fixed: vendor fix RHSA-2026:74438
  • Red Hat Enterprise Linux Real Time (v. 10) kernel-rt 6.12.0-211.63.1.el10_2, kernel-rt-64k 6.12.0-211.63.1.el10_2, kernel-rt-core 6.12.0-211.63.1.el10_2, kernel-rt-modules 6.12.0-211.63.1.el10_2, kernel-rt-64k-core 6.12.0-211.63.1.el10_2, kernel-rt-debug-core 6.12.0-211.63.1.el10_2, +14 more
    fixed: vendor fix RHSA-2026:76738
  • Red Hat Enterprise Linux Real Time for NFV (v. 9) kernel-rt 5.14.0-687.54.1.el9_8, kernel-rt-core 5.14.0-687.54.1.el9_8, kernel-rt-modules 5.14.0-687.54.1.el9_8, kernel-rt-debug-core 5.14.0-687.54.1.el9_8, kernel-rt-modules-core 5.14.0-687.54.1.el9_8, kernel-rt-debug-modules 5.14.0-687.54.1.el9_8, +4 more
    fixed: vendor fix RHSA-2026:74438
  • Red Hat Enterprise Linux Real Time for NFV (v. 10) kernel-rt 6.12.0-211.63.1.el10_2, kernel-rt-core 6.12.0-211.63.1.el10_2, kernel-rt-modules 6.12.0-211.63.1.el10_2, kernel-rt-debug-core 6.12.0-211.63.1.el10_2, kernel-rt-modules-core 6.12.0-211.63.1.el10_2, kernel-rt-debug-modules 6.12.0-211.63.1.el10_2, +4 more
    fixed: vendor fix RHSA-2026:76738
  • Red Hat Enterprise Linux RT (v. 8) kernel-rt 4.18.0-553.171.1.rt7.512.el8_10, kernel-rt-core 4.18.0-553.171.1.rt7.512.el8_10, kernel-rt-modules 4.18.0-553.171.1.rt7.512.el8_10, kernel-rt-debug-core 4.18.0-553.171.1.rt7.512.el8_10, kernel-rt-debug-modules 4.18.0-553.171.1.rt7.512.el8_10, kernel-rt-modules-extra 4.18.0-553.171.1.rt7.512.el8_10, +2 more
    fixed: vendor fix RHSA-2026:75746

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
partial
Assessed
23 d ago

Exploit prediction

0.19% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.1 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Affected products

  • Linux Linux

Classification

Weakness
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.