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VulnerabilityPublished Updated

CVE-2026-64296: Linux kernel · exfat: bound uniname advance in exfat_find_dir_entry()

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4 : patch Linux kernel soon.

Data as of 26 Oct 2026, 17:30 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4, cf85180b8a015029ee147694eaf4e0b3537e9432, ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0 +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ ca06197382bde0a3bc20215595d1c9ce20c6e341, < fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4
Fixed in
  • fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4
LinuxLinuxAffected
  • ≥ ca06197382bde0a3bc20215595d1c9ce20c6e341, < cf85180b8a015029ee147694eaf4e0b3537e9432
Fixed in
  • cf85180b8a015029ee147694eaf4e0b3537e9432
LinuxLinuxAffected
  • ≥ ca06197382bde0a3bc20215595d1c9ce20c6e341, < ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0
Fixed in
  • ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0
LinuxLinuxAffected
  • ≥ ca06197382bde0a3bc20215595d1c9ce20c6e341, < c8e041c68c0bbb73aa62371ee63947bb6949d8b2
Fixed in
  • c8e041c68c0bbb73aa62371ee63947bb6949d8b2
LinuxLinuxAffected
  • ≥ ca06197382bde0a3bc20215595d1c9ce20c6e341, < 727bf7783a2936ffd55c628dddfd69343e511dcf
Fixed in
  • 727bf7783a2936ffd55c628dddfd69343e511dcf
LinuxLinuxAffected
  • ≥ ca06197382bde0a3bc20215595d1c9ce20c6e341, < 72a2589d82eb001c94b74bcfe6f9a599bd9bef60
Fixed in
  • 72a2589d82eb001c94b74bcfe6f9a599bd9bef60

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.

References

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