CVE-2026-53390Network attack vector

Kernel disclosure and crash via undersized SMB ACE

Published Jul 19, 2026 · Updated Jul 19, 2026

Out-of-bounds read in Linux Kernel ksmbd allows remote authenticated users to read past a heap allocation through crafted SMB2 ACEs. The smb_check_perm_dacl() ACE walk accepts a SID sub-authority count that exceeds the declared ACE size, and compare_sids() then reads past the pntsd allocation. Access requires an authenticated SMB2 session with share access and ACL xattrs; the over-read can disclose adjacent heap data or crash the kernel.

CVSS severity8.1
High
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in Linux Kernel ksmbd allows remote authenticated users to read past a heap allocation through crafted SMB2 ACEs. The smb_check_perm_dacl() ACE walk accepts a SID sub-authority count that exceeds the declared ACE size, and compare_sids() then reads past the pntsd allocation. Access requires an authenticated SMB2 session with share access and ACL xattrs; the over-read can disclose adjacent heap data or crash the kernel.

The record

CVE
CVE-2026-53390
Published
Jul 19, 2026
Updated
Jul 19, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-125, T1210
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=151b1799861fde38087c08f613abc2843ef597b0
  2. Affected versionversion=282cbbb476b9f35793452bc461934af4c7eca169
  3. Affected versionversion=325d4ac11f526cb8964cff14548ccf02d8c756d8 <36599894fa8536fefdf1e296c0af71b8b7226859
  4. Affected versionversion=5.15.210 <5.16
  5. Affected versionversion=6.1.176 <6.1.177
  6. Affected versionversion=6.12.84 <6.12.95
  7. Affected versionversion=6.18.25 <6.18.38
  8. Affected versionversion=6.6.140 <6.6.144
  9. Affected versionversion=7.0.2 <7.1
  10. Affected versionversion=7.1
  11. Affected versionversion=90089584b2e25c4510b7b987387b4405f0673ece <7627ff8c4f9919f14de562b0160ab4ec9d80b1f7
  12. Affected versionversion=95e5aa3c3261da8c95b27d7aecf8ee39b9f86a4c <d5c81a095c86fe507c032d08f3a8cfc518444927
  13. Affected versionversion=d07b26f39246a82399661936dd0c853983cfade7 <1ef06004ed4bd6d3ed8c840d9d1a376b66d4935b
  14. Affected versionversion=d07b26f39246a82399661936dd0c853983cfade7 <e36e35660adb9b8ef1435ac359151dda5f094c55
  15. Affected versionversion=f20adc4ef7428bc485ee83fd1a592252fb87718b <988c93d3bba066d8669143e6ec30bb2be9608d53

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=151b1799861fde38087c08f613abc2843ef597b0; version=282cbbb476b9f35793452bc461934af4c7eca169; version=325d4ac11f526cb8964cff14548ccf02d8c756d8 <36599894fa8536fefdf1e296c0af71b8b7226859; version=5.15.210 <5.16; version=6.1.176 <6.1.177; version=6.12.84 <6.12.95; version=6.18.25 <6.18.38; version=6.6.140 <6.6.144; version=7.0.2 <7.1; version=7.1; version=90089584b2e25c4510b7b987387b4405f0673ece <7627ff8c4f9919f14de562b0160ab4ec9d80b1f7; version=95e5aa3c3261da8c95b27d7aecf8ee39b9f86a4c <d5c81a095c86fe507c032d08f3a8cfc518444927; version=d07b26f39246a82399661936dd0c853983cfade7 <1ef06004ed4bd6d3ed8c840d9d1a376b66d4935b; version=d07b26f39246a82399661936dd0c853983cfade7 <e36e35660adb9b8ef1435ac359151dda5f094c55; version=f20adc4ef7428bc485ee83fd1a592252fb87718b <988c93d3bba066d8669143e6ec30bb2be9608d53

Published CVSS scores

8.1kernel.orgCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-125Out-of-bounds Read
T1210Exploitation of Remote Services

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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