CVE-2024-49996: cifs: Fix buffer overflow when parsing NFS reparse points

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-10-21 · updated 2026-08-04
Weakness: CWE-120

Description

In the Linux kernel, the following vulnerability has been resolved: cifs: Fix buffer overflow when parsing NFS reparse points ReparseDataLength is sum of the InodeType size and DataBuffer size. So to get DataBuffer size it is needed to subtract InodeType's size from ReparseDataLength. Function cifs_strndup_from_utf16() is currentlly accessing buf->DataBuffer at position after the end of the buffer because it does not subtract InodeType size from the length. Fix this problem and correctly subtract variable len. Member InodeType is present only when reparse buffer is large enough. Check for ReparseDataLength before accessing InodeType to prevent another invalid memory access. Major and minor rdev values are present also only when reparse buffer is large enough. Check for reparse buffer size before calling reparse_mkdev().

Affected products

Debian Linux: 11.0
Linux kernel: from 5.3 before 5.4.287; from 5.5 before 5.10.231; from 5.11 before 5.15.174; from 5.16 before 6.1.120; from 6.2 before 6.6.55; from 6.7 before 6.10.14 — fixed in 5.10.231, 5.15.174, 5.4.287, 6.1.120, 6.10.14, 6.11.3

How to fix

Upgrade to a fixed version: Linux kernel 5.10.231, 5.15.174, 5.4.287, 6.1.120. Check the vendor advisory for mitigations.

References

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