CVE-2025-39694

Kernel disclosure and crash via translated NULL check

Published Sep 5, 2025 · Updated Sep 5, 2025

An invalid memory access in affected Linux kernel builds starting with 5.16 allows local users to disclose kernel memory or crash s390 systems. The SCLP interrupt handler translates a zero SCCB physical address before testing it, so a nonzero identity-map base defeats the NULL guard and accesses the first mapped page. An ordinary local account can drive SCLP event traffic; the resulting bad length can copy kernel lowcore data into trace buffers or panic the kernel.

CVSS severity7.3
High
EPSS probability0.16%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An invalid memory access in affected Linux kernel builds starting with 5.16 allows local users to disclose kernel memory or crash s390 systems. The SCLP interrupt handler translates a zero SCCB physical address before testing it, so a nonzero identity-map base defeats the NULL guard and accesses the first mapped page. An ordinary local account can drive SCLP event traffic; the resulting bad length can copy kernel lowcore data into trace buffers or panic the kernel.

The record

CVE
CVE-2025-39694
Published
Sep 5, 2025
Updated
Sep 5, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 5, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 5, 2025Record 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=5.16
  2. Affected versionversion=ada1da31ce34248bc97ca8f801f2cf6efa378a81 <430fa71027b6ac9bb0ce5532b8d0676777d4219a
  3. Affected versionversion=ada1da31ce34248bc97ca8f801f2cf6efa378a81 <61605c847599fbfdfafe638607841c7d73719081
  4. Affected versionversion=ada1da31ce34248bc97ca8f801f2cf6efa378a81 <86c2825791c3836a8f77a954b9c5ebe6fab410c5
  5. Affected versionversion=ada1da31ce34248bc97ca8f801f2cf6efa378a81 <aa5073ac1a2a274812f3b04c278992e68ff67cc7
  6. Affected versionversion=ada1da31ce34248bc97ca8f801f2cf6efa378a81 <bf83ae3537359af088d6577812ed93113dfbcb7b

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=5.16; version=ada1da31ce34248bc97ca8f801f2cf6efa378a81 <430fa71027b6ac9bb0ce5532b8d0676777d4219a; version=ada1da31ce34248bc97ca8f801f2cf6efa378a81 <61605c847599fbfdfafe638607841c7d73719081; version=ada1da31ce34248bc97ca8f801f2cf6efa378a81 <86c2825791c3836a8f77a954b9c5ebe6fab410c5; version=ada1da31ce34248bc97ca8f801f2cf6efa378a81 <aa5073ac1a2a274812f3b04c278992e68ff67cc7; version=ada1da31ce34248bc97ca8f801f2cf6efa378a81 <bf83ae3537359af088d6577812ed93113dfbcb7b

Published CVSS scores

7.3LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Endpoint Denial of Service: Application 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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