CVE-2026-31613

Technical Description

In the Linux kernel, the following vulnerability has been resolved:

smb: client: fix OOB reads parsing symlink error response

When a CREATE returns STATUS_STOPPED_ON_SYMLINK, smb2_check_message()

returns success without any length validation, leaving the symlink

parsers as the only defense against an untrusted server.

symlink_data() walks SMB 3.1.1 error contexts with the loop test "p <

end", but reads p->ErrorId at offset 4 and p->ErrorDataLength at offset

0. When the server-controlled ErrorDataLength advances p to within 1-7

bytes of end, the next iteration will read past it. When the matching

context is found, sym->SymLinkErrorTag is read at offset 4 from

p->ErrorContextData with no check that the symlink header itself fits.

smb2_parse_symlink_response() then bounds-checks the substitute name

using SMB2_SYMLINK_STRUCT_SIZE as the offset of PathBuffer from

iov_base. That value is computed as sizeof(smb2_err_rsp) +

sizeof(smb2_symlink_err_rsp), which is correct only when

ErrorC

Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected Products

References