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VulnerabilityPublished Updated

CVE-2026-45856: Linux kernel · RDMA/uverbs: Validate wqe_size before using it in ib_uverbs_post_send

Affects Linux kernelSource CVE Database V5

0

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

CVSS 3.1 base score
7.1High
How severe the flaw is on the 0–10 CVSS scale.
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:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 May 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ c3bea3d2dc5358e05541527283279102383b0231, < d533425ac1f2925b4fc3e4ed9b9d72362cb23475
Fixed in
  • d533425ac1f2925b4fc3e4ed9b9d72362cb23475
LinuxLinuxAffected
  • ≥ c3bea3d2dc5358e05541527283279102383b0231, < bf4454da8b1e712714628c0a0d6e7845bb40790a
Fixed in
  • bf4454da8b1e712714628c0a0d6e7845bb40790a
LinuxLinuxAffected
  • ≥ c3bea3d2dc5358e05541527283279102383b0231, < bf1feed1a7886af945f92890493aefd2b5c9928a
Fixed in
  • bf1feed1a7886af945f92890493aefd2b5c9928a
LinuxLinuxAffected
  • ≥ c3bea3d2dc5358e05541527283279102383b0231, < bef70ff9841990658610512b4a18e4a88c9b4df6
Fixed in
  • bef70ff9841990658610512b4a18e4a88c9b4df6
LinuxLinuxAffected
  • ≥ c3bea3d2dc5358e05541527283279102383b0231, < 1956f0a74ccf5dc9c3ef717f2985c3ed3400aab0
Fixed in
  • 1956f0a74ccf5dc9c3ef717f2985c3ed3400aab0
LinuxLinuxAffected
  • ≥ c3bea3d2dc5358e05541527283279102383b0231, < 9c15ec4cd4e7f57c6bbcb4e73e99290f150dd2a7
Fixed in
  • 9c15ec4cd4e7f57c6bbcb4e73e99290f150dd2a7

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

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