CVE-2026-45856: Linux kernel · RDMA/uverbs: Validate wqe_size before using it in ib_uverbs_post_send
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 7.1 High · fixed in d533425ac1f2925b4fc3e4ed9b9d72362cb23475 : patch Linux kernel soon.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 8% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in d533425ac1f2925b4fc3e4ed9b9d72362cb23475, bf4454da8b1e712714628c0a0d6e7845bb40790a, bf1feed1a7886af945f92890493aefd2b5c9928a +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 27 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Description
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).
References
- git.kernel.org/stable/c/9c15ec4cd4e7f57c6bbcb4e73e99290f150dd2a7 (opens in a new tab)
- git.kernel.org/stable/c/9b5ac1c15334d46c0dbd49d64a2257b929500163 (opens in a new tab)
- git.kernel.org/stable/c/01c9b152647dc70dc06a4a2eff86ebb3b3c76075 (opens in a new tab)
- git.kernel.org/stable/c/bf1feed1a7886af945f92890493aefd2b5c9928a (opens in a new tab)
- git.kernel.org/stable/c/d533425ac1f2925b4fc3e4ed9b9d72362cb23475 (opens in a new tab)
- git.kernel.org/stable/c/bf4454da8b1e712714628c0a0d6e7845bb40790a (opens in a new tab)
- git.kernel.org/stable/c/bef70ff9841990658610512b4a18e4a88c9b4df6 (opens in a new tab)
- git.kernel.org/stable/c/1956f0a74ccf5dc9c3ef717f2985c3ed3400aab0 (opens in a new tab)