CVE-2026-99274: Linux kernel · smb: client: fix fiemap wild read on empty truncated response
Affects Linux kernelSource GCVE Database
Not known to be exploited.
Data as of 10 Nov 2026, 07:11 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
Thin evidence
One scorer or noneExploitation evidence
Disclosed: evidence found.
CVE published 7 Nov 2026
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 9 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.10linuxpkg:deb/ubuntu/linux?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=stonkingOther threats | Affected
| Fixed in– |
Ubuntu 26.10linux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=stonkingOther threats | Affected
| 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 fix for this vulnerability is available and should be applied. The patch rejects empty truncated range blobs and adds necessary checks to prevent wild reads and infinite loops. Users should update to fixed kernel versions or apply the vendor's official patches. No additional mitigation is required beyond applying the fix.
Description
A vulnerability in the Linux kernel SMB client (smb3_fiemap) allows a wild read from an empty truncated response when handling FSCTL_QUERY_ALLOCATED_RANGES requests. This occurs because the client incorrectly processes a STATUS_BUFFER_OVERFLOW response with zero output count, leading to an out-of-bounds memory read and potential kernel crash (oops). The issue has been reproduced on version 6.6.87.2 with a malicious SMB2 server. The vulnerability is fixed by rejecting empty truncated range blobs and adding additional checks to prevent infinite loops and memory underflows.
References
- ubuntu.com/security/CVE-2026-99274 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-99274 (opens in a new tab)
- git.kernel.org/stable/c/4a426ca5be7e3dedbe76575b967db04fbf01136f (opens in a new tab)
- git.kernel.org/stable/c/f5baa17a0f316c235d61623ac8e8fb32c2b3c0cc (opens in a new tab)
- git.kernel.org/stable/c/31f6dbb29fe17fa9595c7e8b19fd92915b03a4ca (opens in a new tab)