CVE-2026-64296
Analyzed
Analyzed - Analysis Complete
Buffer Overflow in Linux Kernel exFAT Driver
Vulnerability report for CVE-2026-64296, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-07-25
Last updated on: 2026-08-12
Assigner: kernel.org
Description
Description
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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | From 5.11 (inc) to 5.15.212 (exc) |
| linux | linux_kernel | From 5.16 (inc) to 6.1.178 (exc) |
| linux | linux_kernel | From 6.2 (inc) to 6.6.145 (exc) |
| linux | linux_kernel | From 6.7 (inc) to 6.12.96 (exc) |
| linux | linux_kernel | From 6.13 (inc) to 6.18.39 (exc) |
| linux | linux_kernel | From 6.19 (inc) to 7.1.4 (exc) |
| linux | linux_kernel | From 5.7 (inc) to 5.10.261 (exc) |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
