RDMA/uverbs: Validate wqe_size before using it in ib_uverbs_post_send
Priority LOW 30CWE-125Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · None · High
- Fix status
- Partial Red Hat: 16 fixed, 3 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat.
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).
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00187 8th percentileScored 2026-11-07
Fix Partial Linux (Linux): 5.10.252, 5.15.202, 6.1.165 +5Red Hat: 4 advisoriesRed Hat: 16 fixed, 3 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Linux | Linux | 5.0 and later | 5.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.14, 6.19.4, 7.0 | Patch available | CNA |
- Linux VendorLinux Affected 5.0 and later Fixed in 5.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.14, 6.19.4, 7.0 Patch available CNA
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | 5.0 to before 5.10.252; 5.11 to before 5.15.202; 5.16 to before 6.1.165; 6.2 to before 6.6.128; 6.7 to before 6.12.75; 6.13 to before 6.18.14; 6.19 to before 6.19.4 | Vulnerable | Linux |
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions 5.0 to before 5.10.252; 5.11 to before 5.15.202; 5.16 to before 6.1.165; 6.2 to before 6.6.128; 6.7 to before 6.12.75; 6.13 to before 6.18.14; 6.19 to before 6.19.4 Vulnerable ·Linux
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.14, 6.19.4, 7.0
Red Hat 4 advisories
- RHSA-2026:76738 Released 2026-10-08 · Red Hat rating Importantkernel security, bug fix, and enhancement update
- 10Base-SMTV kernel-modules-internal-6.12.0-211.63.1.el10_2
- Red Hat Enterprise Linux AppStream (v. 10) kernel-64k-debug-devel-6.12.0-211.63.1.el10_2, kernel-64k-debug-devel-matched-6.12.0-211.63.1.el10_2, kernel-64k-devel-6.12.0-211.63.1.el10_2 +12
- 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-64k-core-6.12.0-211.63.1.el10_2 +29
- Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) kernel-tools-libs-devel-6.12.0-211.63.1.el10_2, libperf-6.12.0-211.63.1.el10_2
- Red Hat Enterprise Linux Hidden (v. 10) kernel-modules-internal-6.12.0-211.63.1.el10_2
- 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-64k-core-6.12.0-211.63.1.el10_2 +21
- 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-debug-6.12.0-211.63.1.el10_2 +9
- RHSA-2026:75747 Released 2026-10-05 · Red Hat rating Importantkernel security, bug fix, and enhancement update
- Red Hat Enterprise Linux BaseOS (v. 8) bpftool-4.18.0-553.171.1.el8_10, kernel-4.18.0-553.171.1.el8_10, kernel-abi-stablelists-4.18.0-553.171.1.el8_10 +19
- Red Hat Enterprise Linux CRB (v. 8) kernel-tools-libs-devel-4.18.0-553.171.1.el8_10
- RHSA-2026:75746 Released 2026-10-05 · Red Hat rating Importantkernel-rt security, bug fix, and enhancement update
- Red Hat Enterprise Linux NFV (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-debug-4.18.0-553.171.1.rt7.512.el8_10 +9
- 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-debug-4.18.0-553.171.1.rt7.512.el8_10 +7
Show 1 more Red Hat advisories
- RHSA-2026:74438 Released 2026-10-02 · Red Hat rating Moderatekernel security, bug fix, and enhancement update
- Red Hat Enterprise Linux AppStream (v. 9) kernel-64k-debug-devel-5.14.0-687.54.1.el9_8, kernel-64k-debug-devel-matched-5.14.0-687.54.1.el9_8, kernel-64k-devel-5.14.0-687.54.1.el9_8 +12
- 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-64k-core-5.14.0-687.54.1.el9_8 +28
- Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) kernel-tools-libs-devel-5.14.0-687.54.1.el9_8, libperf-5.14.0-687.54.1.el9_8
- 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-64k-core-5.14.0-687.54.1.el9_8 +21
- 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-debug-5.14.0-687.54.1.el9_8 +9
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| 10Base-SMTV | Fixed | RHSA-2026:76738 |
| Red Hat Enterprise Linux AppStream (v. 10) | Fixed | RHSA-2026:76738 |
| Red Hat Enterprise Linux AppStream (v. 9) | Fixed | RHSA-2026:74438 |
| Red Hat Enterprise Linux BaseOS (v. 10) | Fixed | RHSA-2026:76738 |
| Red Hat Enterprise Linux BaseOS (v. 8) | Fixed | RHSA-2026:75747 |
| Red Hat Enterprise Linux BaseOS (v. 9) | Fixed | RHSA-2026:74438 |
| Red Hat Enterprise Linux CRB (v. 8) | Fixed | RHSA-2026:75747 |
| Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) | Fixed | RHSA-2026:76738 |
| Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) | Fixed | RHSA-2026:74438 |
| Red Hat Enterprise Linux Hidden (v. 10) | Fixed | RHSA-2026:76738 |
| Red Hat Enterprise Linux NFV (v. 8) | Fixed | RHSA-2026:75746 |
| Red Hat Enterprise Linux RT (v. 8) | Fixed | RHSA-2026:75746 |
| Red Hat Enterprise Linux Real Time (v. 10) | Fixed | RHSA-2026:76738 |
| Red Hat Enterprise Linux Real Time (v. 9) | Fixed | RHSA-2026:74438 |
| Red Hat Enterprise Linux Real Time for NFV (v. 10) | Fixed | RHSA-2026:76738 |
| Red Hat Enterprise Linux Real Time for NFV (v. 9) | Fixed | RHSA-2026:74438 |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-45856
- 2026-10-03 Alias added: GHSA-xq3r-74hw-4c5p
- 2026-10-05 Fix available: RHSA-2026:75746 · Red Hat
- 2026-10-05 Fix available: RHSA-2026:75747 · Red Hat
- 2026-10-05 Fix available: Red Hat Enterprise Linux BaseOS (v. 8), Red Hat Enterprise Linux CRB (v. 8), Red Hat Enterprise Linux NFV (v. 8) +1 · Red Hat
- 2026-10-16 CISA SSVC decision points changed
- 2026-10-19 Weakness changed · CISA ADP
- 2026-10-26 Fix available: RHSA-2026:76738 · Red Hat
- 2026-10-26 Fix available: 10Base-SMTV, Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10) +4 · Red Hat
- 2026-11-06 CVSS score changed · Red Hat
References
Patch 8
- https://git.kernel.org/stable/c/9c15ec4cd4e7f57c6bbcb4e73e99290f150dd2a7
- https://git.kernel.org/stable/c/9b5ac1c15334d46c0dbd49d64a2257b929500163
- https://git.kernel.org/stable/c/01c9b152647dc70dc06a4a2eff86ebb3b3c76075
- https://git.kernel.org/stable/c/bf1feed1a7886af945f92890493aefd2b5c9928a
- https://git.kernel.org/stable/c/d533425ac1f2925b4fc3e4ed9b9d72362cb23475
- https://git.kernel.org/stable/c/bf4454da8b1e712714628c0a0d6e7845bb40790a
- https://git.kernel.org/stable/c/bef70ff9841990658610512b4a18e4a88c9b4df6
- https://git.kernel.org/stable/c/1956f0a74ccf5dc9c3ef717f2985c3ed3400aab0
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Sources
- CVE-2026-45856 · CVE Program
- CVE-2026-45856 · NVD
- FIRST EPSS
- GHSA-xq3r-74hw-4c5p · GitHub Advisory Database · CC BY 4.0
- CVE-2026-45856 · Red Hat security data · CC BY 4.0
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