CVE-2026-99274
Received
Received - Intake
Linux kernel SMB client fiemap buffer overflow fix
Vulnerability report for CVE-2026-99274, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-11-07
Last updated on: 2026-11-07
Assigner: kernel.org
Description
Description
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix fiemap wild read on empty truncated response
smb3_fiemap() treats -E2BIG from SMB2_ioctl() as a truncated range blob
and loops for the next chunk. If the server reports
STATUS_BUFFER_OVERFLOW with OutputCount == 0, SMB2_ioctl() returns
-E2BIG with out_data == NULL and out_data_len == 0, and the existing
length checks accept the empty result. The loop then evaluates
next = out_data[num - 1].file_offset + ...
with num == 0, reading 16 bytes before NULL.
Reject a truncated range blob that contains no range, so the resume
offset is never computed from an empty response. Also require the last
range in a truncated blob to advance the resume offset without
overflowing, and to stay within the requested range; a malicious or
broken server could otherwise make no progress or underflow len and loop
forever. Free the previous response buffer before retrying.
Reproduced on 6.6.87.2 with a malicious SMB2 server that answers
FSCTL_QUERY_ALLOCATED_RANGES with STATUS_BUFFER_OVERFLOW and
OutputCount == 0; an FS_IOC_FIEMAP ioctl on the mount oopses in
cifs_fiemap() with CR2 = fffffffffffffff8. The code path is unchanged
on mainline.
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
Currently, no data is known.
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
