CVE-2026-64296 — linux / linux_kernel
In the Linux kernel, the following vulnerability has been resolved:
exfat: bound uniname advance in exfat_find_dir_entry()
In exfat_find_dir_entry(), each TYPE_EXTEND (file name) entry advances the output pointer by a fixed amount while the loop guard only tracks the accumulated name length:
if (++order == 2)
uniname = p_uniname->name;
else
uniname += EXFAT_FILE_NAME_LEN;
len = exfat_extract_uni_name(ep, entry_uniname);
name_len += len;
unichar = *(uniname+len);
*(uniname+len) = 0x0;
uniname grows by EXFAT_FILE_NAME_LEN (15) per name entry, but name_len
grows only by the actual extracted length, which is shorter when a name
fragment contains an early NUL. The only guard is
name_len >= MAX_NAME_LENGTH, so a crafted directory with many short
name fragments lets uniname run far past the
p_uniname->name[MAX_NAME_LENGTH + 3] buffer while name_len stays small,
causing an out-of-bounds read and write at *(uniname+len).
The sibling extractor exfat_get_uniname_from_ext_entry() already stops
on a short fragment (the lockstep len != EXFAT_FILE_NAME_LEN guard
added in commit d42334578eba ("exfat: check if filename entries exceeds
max filename length")); exfat_find_dir_entry() never got the
equivalent. Track the per-entry write offset as a count and reject a
fragment once the offset, or the offset plus the extracted length, would
exceed MAX_NAME_LENGTH, before forming the output pointer.
| Software | From | Fixed in |
|---|---|---|
| linux / linux_kernel | 5.7 | 5.10.261 |
| linux / linux_kernel | 5.11 | 5.15.212 |
| linux / linux_kernel | 5.16 | 6.1.178 |
| linux / linux_kernel | 6.2 | 6.6.145 |
| linux / linux_kernel | 6.7 | 6.12.96 |
| linux / linux_kernel | 6.13 | 6.18.39 |
| linux / linux_kernel | 6.19 | 7.1.4 |
- https://git.kernel.org/stable/c/33c0b96d7e1672be1de0053786637ea46fb81507
- https://git.kernel.org/stable/c/3a1230e7b043c62737b05a3e9275ca83a43ad20a
- https://git.kernel.org/stable/c/727bf7783a2936ffd55c628dddfd69343e511dcf
- https://git.kernel.org/stable/c/72a2589d82eb001c94b74bcfe6f9a599bd9bef60
- https://git.kernel.org/stable/c/c8e041c68c0bbb73aa62371ee63947bb6949d8b2
- https://git.kernel.org/stable/c/ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0
- https://git.kernel.org/stable/c/cf85180b8a015029ee147694eaf4e0b3537e9432
- https://git.kernel.org/stable/c/fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4
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