CVE-2025-39819: Linux kernel · fs/smb: Fix inconsistent refcnt update
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in cc82c6dff548f0066a51a6e577c7454e7d26a968 : update Linux kernel when convenient.
Data as of 5 Nov 2026, 21:35 UTC
Rated Low by Threat Radar's AI analysis · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-11-05.
- Patch
- Available – fixed in cc82c6dff548f0066a51a6e577c7454e7d26a968, ab529e6ca1f67bcf31f3ea80c72bffde2e9e053e, 4735f5991f51468b85affb8366b7067248457a71 +2
Exploitation evidence
Disclosed: evidence found.
CVE published 16 Sep 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 5 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in– |
AI-suggested
This issue has been fixed in the Linux kernel. Users should update to the fixed versions identified by the commits cc82c6dff548f0066a51a6e577c7454e7d26a968, ab529e6ca1f67bcf31f3ea80c72bffde2e9e053e, 4735f5991f51468b85affb8366b7067248457a71, 4191ea1f0bb3e27d65c5dcde7bd00e709ec67141, and 3fc11ff13fbc2749871d6ac2141685cf54699997. The affected version is 5.8. No additional mitigation is required once patched.
Description
A vulnerability in the Linux kernel's SMB filesystem code caused inconsistent reference count updates in the smb2_compound_op function. This flaw could lead to resource leaks due to improper cleanup when memory allocation fails. The issue was fixed by adding a cleanup path to ensure references are properly dropped even on allocation failure.
References
- git.kernel.org/stable/c/3fc11ff13fbc2749871d6ac2141685cf54699997 (opens in a new tab)
- git.kernel.org/stable/c/4191ea1f0bb3e27d65c5dcde7bd00e709ec67141 (opens in a new tab)
- git.kernel.org/stable/c/4735f5991f51468b85affb8366b7067248457a71 (opens in a new tab)
- git.kernel.org/stable/c/cc82c6dff548f0066a51a6e577c7454e7d26a968 (opens in a new tab)
- git.kernel.org/stable/c/ab529e6ca1f67bcf31f3ea80c72bffde2e9e053e (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/10/msg00008.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-032379.html (opens in a new tab)