Linux Kernel up to 6.19.3 uverbs ib_uverbs_post_send out-of-bounds

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.2	$0-$5k	0.00

Summaryinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.19.3. Affected by this issue is the function ib_uverbs_post_send of the component uverbs. The manipulation results in out-of-bounds. This vulnerability is cataloged as CVE-2026-45856. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Linux Kernel up to 6.19.3. Affected is the function ib_uverbs_post_send of the component uverbs. The manipulation with an unknown input leads to a out-of-bounds vulnerability. CWE is classifying the issue as CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. This is going to have an impact on confidentiality. CVE summarizes:

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).

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2026-45856 since 05/13/2026. The exploitability is told to be easy. Technical details are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 321697 (SUSE SLES16 Security Update : kernel (SUSE-SU-2026:22099-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.14 or 6.19.4 eliminates this vulnerability. Applying the patch 9c15ec4cd4e7f57c6bbcb4e73e99290f150dd2a7/9b5ac1c15334d46c0dbd49d64a2257b929500163/01c9b152647dc70dc06a4a2eff86ebb3b3c76075/bf1feed1a7886af945f92890493aefd2b5c9928a/d533425ac1f2925b4fc3e4ed9b9d72362cb23475/bf4454da8b1e712714628c0a0d6e7845bb40790a/bef70ff9841990658610512b4a18e4a88c9b4df6/1956f0a74ccf5dc9c3ef717f2985c3ed3400aab0 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (321697) and CERT Bund (WID-SEC-2026-1700). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• Google Container-Optimized OS
• Debian Linux
• Amazon Linux 2
• Red Hat Enterprise Linux
• Ubuntu Linux
• SUSE Linux
• Oracle Linux
• SUSE openSUSE
• RESF Rocky Linux
• Open Source Linux Kernel
• Siemens SIMATIC S7

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.10.251
• 5.15.201
• 6.1.164
• 6.6.127
• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
• 6.12.8
• 6.12.9
• 6.12.10
• 6.12.11
• 6.12.12
• 6.12.13
• 6.12.14
• 6.12.15
• 6.12.16
• 6.12.17
• 6.12.18
• 6.12.19
• 6.12.20
• 6.12.21
• 6.12.22
• 6.12.23
• 6.12.24
• 6.12.25
• 6.12.26
• 6.12.27
• 6.12.28
• 6.12.29
• 6.12.30
• 6.12.31
• 6.12.32
• 6.12.33
• 6.12.34
• 6.12.35
• 6.12.36
• 6.12.37
• 6.12.38
• 6.12.39
• 6.12.40
• 6.12.41
• 6.12.42
• 6.12.43
• 6.12.44
• 6.12.45
• 6.12.46
• 6.12.47
• 6.12.48
• 6.12.49
• 6.12.50
• 6.12.51
• 6.12.52
• 6.12.53
• 6.12.54
• 6.12.55
• 6.12.56
• 6.12.57
• 6.12.58
• 6.12.59
• 6.12.60
• 6.12.61
• 6.12.62
• 6.12.63
• 6.12.64
• 6.12.65
• 6.12.66
• 6.12.67
• 6.12.68
• 6.12.69
• 6.12.70
• 6.12.71
• 6.12.72
• 6.12.73
• 6.12.74
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.19.0
• 6.19.1
• 6.19.2
• 6.19.3

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.2

VulDB Base Score: 3.5
VulDB Temp Score: 3.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.1
CNA Vector (Linux): 🔒

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Out-of-bounds
CWE: CWE-125 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: Partially
Local: Yes
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 321697
Nessus Name: SUSE SLES16 Security Update : kernel (SUSE-SU-2026:22099-1)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.10.252/5.15.202/6.1.165/6.6.128/6.12.75/6.18.14/6.19.4
Patch: 9c15ec4cd4e7f57c6bbcb4e73e99290f150dd2a7/9b5ac1c15334d46c0dbd49d64a2257b929500163/01c9b152647dc70dc06a4a2eff86ebb3b3c76075/bf1feed1a7886af945f92890493aefd2b5c9928a/d533425ac1f2925b4fc3e4ed9b9d72362cb23475/bf4454da8b1e712714628c0a0d6e7845bb40790a/bef70ff9841990658610512b4a18e4a88c9b4df6/1956f0a74ccf5dc9c3ef717f2985c3ed3400aab0

Timelineinfo

05/13/2026 CVE reserved
05/27/2026 +14 days Advisory disclosed
05/27/2026 +0 days VulDB entry created
07/15/2026 +49 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-45856 (🔒)
GCVE (CVE): GCVE-0-2026-45856
GCVE (VulDB): GCVE-100-366114
CERT Bund: WID-SEC-2026-1700 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 05/27/2026 16:43
Updated: 07/15/2026 08:23
Changes: 05/27/2026 16:43 (59), 06/14/2026 09:48 (7), 06/21/2026 01:51 (2), 06/22/2026 18:25 (1), 06/26/2026 02:42 (11), 07/15/2026 08:23 (1)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Discussion

Are you interested in using VulDB?

Download the whitepaper to learn more about our service!