CVE-2026-64296: Linux kernel · exfat: bound uniname advance in exfat_find_dir_entry()
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 25 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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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
- git.kernel.org/stable/c/72a2589d82eb001c94b74bcfe6f9a599bd9bef60 (opens in a new tab)
- git.kernel.org/stable/c/fae76a94b35ee8c0e2eb6f64caca01d75c6d34e4 (opens in a new tab)
- git.kernel.org/stable/c/cf85180b8a015029ee147694eaf4e0b3537e9432 (opens in a new tab)
- git.kernel.org/stable/c/ce4736c1e6c4cfbf1ac409a8c328a0b69546c9a0 (opens in a new tab)
- git.kernel.org/stable/c/727bf7783a2936ffd55c628dddfd69343e511dcf (opens in a new tab)
- git.kernel.org/stable/c/33c0b96d7e1672be1de0053786637ea46fb81507 (opens in a new tab)
- git.kernel.org/stable/c/c8e041c68c0bbb73aa62371ee63947bb6949d8b2 (opens in a new tab)
- git.kernel.org/stable/c/3a1230e7b043c62737b05a3e9275ca83a43ad20a (opens in a new tab)