CVE-2025-40124

Local privilege escalation via SPARC copy underflow

Published Nov 12, 2025 · Updated Aug 5, 2026

Memory corruption in the Linux SPARC kernel allows local users to gain elevated privileges through a faulting user-memory copy. UltraSPARC III exception handlers calculate uncopied bytes from an unmasked %o2 register, so copy_from_user() or copy_to_user() can return more bytes than requested and underflow iterator accounting. An unprivileged process can deterministically trigger the path with memory mappings and a local system call, causing kernel heap corruption, disclosure, or a panic.

CVSS severity7.8
High
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

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Summary

What happened

Memory corruption in the Linux SPARC kernel allows local users to gain elevated privileges through a faulting user-memory copy. UltraSPARC III exception handlers calculate uncopied bytes from an unmasked %o2 register, so copy_from_user() or copy_to_user() can return more bytes than requested and underflow iterator accounting. An unprivileged process can deterministically trigger the path with memory mappings and a local system call, causing kernel heap corruption, disclosure, or a panic.

The record

CVE
CVE-2025-40124
Published
Nov 12, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1068, T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Nov 12, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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=1c7e17b1c4d60cc5aa575460f7efb73686dd3b39
  2. Affected versionversion=4.4.34 <4.5
  3. Affected versionversion=4.8.10 <4.9
  4. Affected versionversion=4.9
  5. Affected versionversion=ac663c54f40b2830b1ca32d1ae9d683fe248b14c
  6. Affected versionversion=ee841d0aff649164080e445e84885015958d8ff4 <1198077606aeffb102587c6ea079ce99641c99d4
  7. Affected versionversion=ee841d0aff649164080e445e84885015958d8ff4 <1857cdca12c4aff58bf26a7005a4d02850c29927
  8. Affected versionversion=ee841d0aff649164080e445e84885015958d8ff4 <47b49c06eb62504075f0f2e2227aee2e2c2a58b3
  9. Affected versionversion=ee841d0aff649164080e445e84885015958d8ff4 <5ef9c94d7110e90260c06868cf1dcf899b9f25ee
  10. Affected versionversion=ee841d0aff649164080e445e84885015958d8ff4 <91eda032eb16e5d2be27c95584665bc555bb5a90
  11. Affected versionversion=ee841d0aff649164080e445e84885015958d8ff4 <dc766c4830a7e1e1ee9d7f77d4ab344f2eb23c8e
  12. Affected versionversion=ee841d0aff649164080e445e84885015958d8ff4 <e50377c6b3f278c9f3ef017ffce17f5fcc9dace4
  13. Affected versionversion=ee841d0aff649164080e445e84885015958d8ff4 <fdd43fe6d286f27b826572457a89c926f97e2d3a

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1c7e17b1c4d60cc5aa575460f7efb73686dd3b39; version=4.4.34 <4.5; version=4.8.10 <4.9; version=4.9; version=ac663c54f40b2830b1ca32d1ae9d683fe248b14c; version=ee841d0aff649164080e445e84885015958d8ff4 <1198077606aeffb102587c6ea079ce99641c99d4; version=ee841d0aff649164080e445e84885015958d8ff4 <1857cdca12c4aff58bf26a7005a4d02850c29927; version=ee841d0aff649164080e445e84885015958d8ff4 <47b49c06eb62504075f0f2e2227aee2e2c2a58b3; version=ee841d0aff649164080e445e84885015958d8ff4 <5ef9c94d7110e90260c06868cf1dcf899b9f25ee; version=ee841d0aff649164080e445e84885015958d8ff4 <91eda032eb16e5d2be27c95584665bc555bb5a90; version=ee841d0aff649164080e445e84885015958d8ff4 <dc766c4830a7e1e1ee9d7f77d4ab344f2eb23c8e; version=ee841d0aff649164080e445e84885015958d8ff4 <e50377c6b3f278c9f3ef017ffce17f5fcc9dace4; version=ee841d0aff649164080e445e84885015958d8ff4 <fdd43fe6d286f27b826572457a89c926f97e2d3a

Published CVSS scores

7.8kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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

T1068Exploitation for Privilege Escalation
T1499Endpoint Denial of Service

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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