high 7.8

CVE-2026-64296 json

exfat: bound uniname advance in exfat_find_dir_entry()

published 2026-07-25 3 mo ago modified 2026-10-19 20 d ago also EUVD-2026-49008

cvss: 7.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 6%
public exploits: 0; none known

In the Linux kernel, the following vulnerability has been resolved:

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.

Patch / fix

fixed in 1 distros 4 links 8

Linux Linux 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39, 7.1.4, 7.2

debian ubuntu suse opensuse

linux Debian 12 6.1.180-1
linux Debian 13 6.12.96-1
linux Debian 14 7.1.4-1
linux-6.12 Debian 12 6.12.100-1~deb12u1

debian advisories DEBIAN-CVE-2026-64296

linux Ubuntu 22.04 LTS 5.15.0-198.208
linux Ubuntu 24.04 LTS 6.8.0-147.147
linux Ubuntu 26.04 LTS 7.0.0-31.31
linux-aws Ubuntu 22.04 LTS 5.15.0-1117.124
linux-aws Ubuntu 24.04 LTS 6.8.0-1067.70
linux-aws Ubuntu 26.04 LTS 7.0.0-1012.12
linux-gcp Ubuntu 22.04 LTS 5.15.0-1118.128
linux-gcp Ubuntu 24.04 LTS 6.8.0-1071.79

ubuntu advisories UBUNTU-CVE-2026-64296

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.81.1
kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.81.1
kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.81.1
kernel-zfcpdump SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1
kernel-obs-build SLE Module for Development Tools 15 SP7 6.4.0-150700.53.81.1
kernel-default-base SLE Module for Basesystem 15 SP7 6.4.0-150700.53.81.1.150700.17.45.1

suse advisories SUSE-SU-2026:4254-1 SUSE-SU-2026:23887-1 SUSE-SU-2026:23902-1 SUSE-SU-2026:23897-1 SUSE-SU-2026:23881-1 SUSE-SU-2026:4120-1

kernel-rt openSUSE Leap 16.0 6.12.0-160000.38.1
dtb-aarch64 openSUSE Leap 16.0 6.12.0-160000.38.1
kernel-64kb openSUSE Leap 16.0 6.12.0-160000.38.1
kernel-syms openSUSE Leap 16.0 6.12.0-160000.38.1
kernel-azure openSUSE Leap 16.0 6.12.0-160000.38.1
kernel-obs-qa openSUSE Leap 16.0 6.12.0-160000.38.1
kernel-source openSUSE Leap 16.0 6.12.0-160000.38.1
kernel-default openSUSE Leap 16.0 6.12.0-160000.38.1

opensuse advisories openSUSE-SU-2026:21910-1 openSUSE-SU-2026:11476-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-64296 updated 2026-11-07 cvss 6.7

kernel: exfat: bound uniname advance in exfat_find_dir_entry()

Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
affected: no fix available “Fix deferred”
Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: total
Assessed: 23 d ago (2026-10-16)

Exploit prediction

0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	7.8	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

Linux Linux

Classification

Weakness

CWE-787 Out-of-bounds Write

Technology feeds

Linux kernel rss critical rss

References

Sources

CVE List CVE-2026-64296
NVD CVE-2026-64296

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary