CVE-2026-31477Network attack vector

Remote kernel crash via unchecked rollback allocation

Published Apr 22, 2026 · Updated Apr 22, 2026

NULL pointer dereference in Linux Kernel ksmbd allows remote attackers to crash the kernel through crafted SMB lock requests. In smb2_lock(), a failed rollback allocation returns NULL that is dereferenced without a check, while detached lock objects also escape cleanup on two error paths. When ksmbd is enabled and serving SMB clients, unauthenticated network access reaches the handler; the resulting dereference stops the host kernel, and the other paths leak memory.

CVSS severity7.5
High
EPSS probability0.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in Linux Kernel ksmbd allows remote attackers to crash the kernel through crafted SMB lock requests. In smb2_lock(), a failed rollback allocation returns NULL that is dereferenced without a check, while detached lock objects also escape cleanup on two error paths. When ksmbd is enabled and serving SMB clients, unauthenticated network access reaches the handler; the resulting dereference stops the host kernel, and the other paths leak memory.

The record

CVE
CVE-2026-31477
Published
Apr 22, 2026
Updated
Apr 22, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 22, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 22, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.15
  2. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <309b44ed684496ed3f9c5715d10b899338623512
  3. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <3cdacd11b41569ce75b3162142240f2355e04900
  4. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <91aeaa7256006d79a37298f5a1df23325db91599
  5. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <aab42f0795620cf0d3955a520f571f697d0f9a2a
  6. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <c9b95ef6f5039f19e46c3a521a4fe1752d91dfe9
  7. Affected versionversion=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <cdac6f7e7e428dc70e3b5898ac6999a72ed13993

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.15; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <309b44ed684496ed3f9c5715d10b899338623512; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <3cdacd11b41569ce75b3162142240f2355e04900; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <91aeaa7256006d79a37298f5a1df23325db91599; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <aab42f0795620cf0d3955a520f571f697d0f9a2a; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <c9b95ef6f5039f19e46c3a521a4fe1752d91dfe9; version=e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 <cdac6f7e7e428dc70e3b5898ac6999a72ed13993

Published CVSS scores

7.5kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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