CVE-2026-99273
ksmbd: reserve space for the UTF-16 terminator in stream info
What happened?
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: reserve space for the UTF-16 terminator in stream info
smb_strtoUTF16() always writes a terminating zero UTF-16 unit after the converted characters, but get_file_stream_info() budgets only sizeof(struct smb2_file_stream_info) + streamlen * 2 for a stream entry and sizeof(struct smb2_file_stream_info) + 7 * 2 for the trailing "::$DATA" entry. When an entry exactly fills the 448-byte small response buffer, the terminator is written two bytes past the allocation.
Reserve one extra UTF-16 unit in both budget checks. The terminator is not part of the wire format, so the reported lengths are unchanged.
Affected software and versions
| Software | Version information | Fixed version |
|---|---|---|
| LinuxLinux | affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < 583ede545a14f275a959772b5e1e50fe3e14b861; affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < 06a751809ebd33e95b05bf733697318a17a4872b; affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < 0e64f89563164719ceb1aa33f2a8bfd6391fa340; affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 to < a025c4991a7d83edc4dd339e3ea86d8ff6226eca; affected: 0 to < 6.12.117; affected: 0 to < 6.18.61; affected: 0 to < 7.3.2 | See vendor advisory |
| LinuxLinux | unaffected: 6.12.117 to ≤ 6.12.*; unaffected: 6.18.61 to ≤ 6.18.*; unaffected: 7.3.2 to ≤ 7.3.*; unaffected: 7.4-rc1 to ≤ * | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.
Sources and remediation references
- https://www.cve.org/CVERecord?id=CVE-2026-99273
- https://git.kernel.org/stable/c/583ede545a14f275a959772b5e1e50fe3e14b861
- https://git.kernel.org/stable/c/06a751809ebd33e95b05bf733697318a17a4872b
- https://git.kernel.org/stable/c/0e64f89563164719ceb1aa33f2a8bfd6391fa340
- https://git.kernel.org/stable/c/a025c4991a7d83edc4dd339e3ea86d8ff6226eca