CVE-2025-40124: Linux kernel · sparc: fix accurate exception reporting in copy_{from_to}_user for UltraSPARC III
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High · fixed in 5.15.0-1100.107~20.04.2 : patch Linux kernel soon.
Data as of 26 Oct 2026, 11:42 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1100.107~20.04.2, 5.15.0-1110.119~20.04.1, 5.15.0-1100.109~20.04.1 +67
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 12 Nov 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux@6.17.0-14.14?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1007.7?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1008.8?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1007.7?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1007.7?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
In the Linux kernel, the following vulnerability has been resolved: sparc: fix accurate exception reporting in copy_{from_to}_user for UltraSPARC III Anthony Yznaga tracked down that a BUG_ON in ext4 code with large folios enabled resulted from copy_from_user() returning impossibly large values greater than the size to be copied. This lead to __copy_from_iter() returning impossible values instead of the actual number of bytes it was able to copy. The BUG_ON has been reported in https://lore.kernel.org/r/b14f55642207e63e907965e209f6323a0df6dcee.camel@physik.fu-berlin.de The referenced commit introduced exception handlers on user-space memory references in copy_from_user and copy_to_user. These handlers return from the respective function and calculate the remaining bytes left to copy using the current register contents. The exception handlers expect that %o2 has already been masked during the bulk copy loop, but the masking was performed after that loop. This will fix the return value of copy_from_user and copy_to_user in the faulting case. The behaviour of memcpy stays unchanged.
References
- ubuntu.com/security/CVE-2025-40124 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2025-40124 (opens in a new tab)
- git.kernel.org/linus/47b49c06eb62504075f0f2e2227aee2e2c2a58b3 (opens in a new tab)
- git.kernel.org/stable/c/1198077606aeffb102587c6ea079ce99641c99d4 (opens in a new tab)
- git.kernel.org/stable/c/1857cdca12c4aff58bf26a7005a4d02850c29927 (opens in a new tab)
- git.kernel.org/stable/c/47b49c06eb62504075f0f2e2227aee2e2c2a58b3 (opens in a new tab)
- git.kernel.org/stable/c/5ef9c94d7110e90260c06868cf1dcf899b9f25ee (opens in a new tab)
- git.kernel.org/stable/c/91eda032eb16e5d2be27c95584665bc555bb5a90 (opens in a new tab)
- git.kernel.org/stable/c/dc766c4830a7e1e1ee9d7f77d4ab344f2eb23c8e (opens in a new tab)
- git.kernel.org/stable/c/e50377c6b3f278c9f3ef017ffce17f5fcc9dace4 (opens in a new tab)
- git.kernel.org/stable/c/fdd43fe6d286f27b826572457a89c926f97e2d3a (opens in a new tab)
- ubuntu.com/security/notices/USN-8029-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8030-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8034-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-4 (opens in a new tab)
- ubuntu.com/security/notices/USN-8029-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8033-5 (opens in a new tab)