VulnerabilityPublished 4 Feb 2026Updated 22 Aug 2026

CVE-2025-71197: Linux kernel · w1: therm: Fix off-by-one buffer overflow in alarms_store

Affects Linux kernelSource GCVE Database

Not known to be exploited · fixed in 5.15.0-1105.112~20.04.1 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:05 UTC

Severity

Medium

Rated by Threat Radar · No CVSS score from NVD or the CNA

EPSS: 0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 5.15.0-1105.112~20.04.1, 5.15.0-1110.119~20.04.1, 5.15.0-1106.115~20.04.1 +59

Exploitation evidence

Disclosed: evidence found.
CVE published 4 Feb 2026
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.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
Ubuntu 25.10linux`pkg:deb/ubuntu/linux@6.17.0-40.40?arch=source&distro=questing`Other threats	Affected 6.14.0-15.15 – 6.17.0-40.40 20 affected builds	Fixed in–
Ubuntu 25.10linux-aws`pkg:deb/ubuntu/linux-aws@6.17.0-1019.19?arch=source&distro=questing`Other threats	Affected 6.14.0-1005.5 – 6.17.0-1019.19 17 affected builds	Fixed in–
Ubuntu 25.10linux-azure`pkg:deb/ubuntu/linux-azure@6.17.0-1020.20?arch=source&distro=questing`Other threats	Affected 6.14.0-1004.4 – 6.17.0-1020.20 16 affected builds	Fixed in–
Ubuntu 25.10linux-azure-fde`pkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questing`Other threats	Affected 6.17.0-1003.3 – 6.17.0-1017.17 10 affected builds	Fixed in–
Ubuntu 25.10linux-gcp`pkg:deb/ubuntu/linux-gcp@6.17.0-1020.22?arch=source&distro=questing`Other threats	Affected 6.14.0-1006.6 – 6.17.0-1020.22 17 affected builds	Fixed in–
Ubuntu 25.10linux-oracle`pkg:deb/ubuntu/linux-oracle@6.17.0-1018.18?arch=source&distro=questing`Other threats	Affected 6.14.0-1005.5 – 6.17.0-1018.18 16 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch is available and has been released by Ubuntu as part of their Linux kernel updates. Users should update their systems to the fixed kernel versions listed in the vendor advisory and reboot to apply the changes. Due to an ABI change, recompilation and reinstallation of third-party kernel modules may be required. No additional mitigations are specified beyond applying the official updates.

Description

An off-by-one buffer overflow vulnerability in the Linux kernel's w1 therm driver (alarms_store function) was identified and fixed. The issue arose because the sysfs buffer was allocated with 'size + 1' bytes to include a NUL terminator, but the 'size' argument did not account for this extra byte, leading to a buffer overflow when strcpy() copied the buffer. The fix involves parsing the input directly without intermediate copying, eliminating the overflow. This vulnerability affects multiple Linux kernel versions prior to specific patched releases and has been addressed in updated kernel packages. No known exploits are reported in the wild. Users should update to the fixed kernel versions and reboot to apply the changes.

Impact

An attacker could potentially exploit this off-by-one buffer overflow to cause memory corruption, which might lead to system instability or privilege escalation. However, no known exploits in the wild have been reported. The vulnerability affects the Linux kernel's w1 therm driver and could be leveraged to compromise affected systems if left unpatched.

Summary

The Linux kernel's w1 therm driver contained an off-by-one buffer overflow in the alarms_store function. The vulnerability was due to a mismatch between the allocated buffer size and the size argument used in strcpy(), which caused one byte to be written beyond the allocated memory. The fix replaces the unsafe strcpy() call with direct parsing of the input buffer using simple_strtoll(), removing the overflow and simplifying the code. This flaw was resolved in updated Linux kernel packages distributed by Ubuntu, affecting various subsystems and kernel versions prior to 5.15.0-1105.112~20.04.1 and similar versions. The vendor advisory confirms the availability of patches and recommends system updates and reboots to apply the fixes.

GCVE source: db.gcve.eu
OSV ID: UBUNTU-CVE-2025-71197
Osv Schema Version: 1.7.0
Ecosystems: Ubuntu:16.04:LTS, Ubuntu:18.04:LTS, Ubuntu:Pro:18.04:LTS, Ubuntu:20.04:LTS, Ubuntu:Pro:20.04:LTS, Ubuntu:22.04:LTS, Ubuntu:Nvidia-BlueField:22.04:LTS, Ubuntu:Pro:FIPS-preview:22.04:LTS, Ubuntu:Pro:FIPS-updates:22.04:LTS, Ubuntu:Pro:Realtime:22.04:LTS, Ubuntu:24.04:LTS, Ubuntu:Nvidia-BlueField:24.04:LTS, Ubuntu:Pro:FIPS-updates:24.04:LTS, Ubuntu:Pro:Realtime:24.04:LTS, Ubuntu:25.10

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 22 Aug 2026, 22:01 UTC

Technical details

References

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