fs/statmount: fix slab out-of-bounds write in statmount_mnt_idmap (CVE-2026-64074) | HOL Guard CVE

High · CVSS 7.8CVE-2026-64074

fs/statmount: fix slab out-of-bounds write in statmount_mnt_idmap

Answer in brief

CVE-2026-64074 records a High severity (CVSS 7.8) vulnerability in fs/statmount: fix slab out-of-bounds write in statmount_mnt_idmap. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jul 19, 2026Updated Sep 3, 2026Source checked Sep 19, 2026First seen by HOL Aug 5, 2026Material review Sep 3, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.8
Exploitation: Not marked as known exploited
Affected software: 7 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Affected products and reported versions
Product	Affected versions	Fixed versions
cpe:2.3:o:linux:linux_kernel::::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:7.1:rc1::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:7.1:rc2::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:7.1:rc3::::::	Not reported	Not reported
cpe:2.3:o:linux:linux_kernel:7.1:rc4::::::	Not reported	Not reported

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=37c4a9590e1efcae7749682239fc22a330d2d325 <e37ea2c6f17f273813ea4e8e94c102591d598ce1 \|\| >=37c4a9590e1efcae7749682239fc22a330d2d325 <93614949dc86f068e3c32c32cf1ee2a2323177a7 \|\| >=37c4a9590e1efcae7749682239fc22a330d2d325 <a3bf0f28d4ba16e1f35f8c983bb04426b87e2a78	e37ea2c6f17f273813ea4e8e94c102591d598ce1, 93614949dc86f068e3c32c32cf1ee2a2323177a7, a3bf0f28d4ba16e1f35f8c983bb04426b87e2a78
Linux/Linuxgeneric	6.15	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to e37ea2c6f17f273813ea4e8e94c102591d598ce1 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 3, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 5, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: fs/statmount: fix slab out-of-bounds write in statmount_mnt_idmap statmount_mnt_idmap() writes one mapping with seq_printf() and then manually advances seq->count to include the NUL separator. If seq_printf() overflows, seq_set_overflow() sets seq->count to seq->size. The manual seq->count++ changes this to seq->size + 1. seq_has_overflowed() then no longer detects the overflow. The corrupted count returns to statmount_string(), which later executes: seq->buf[seq->count++] = '\0'; This causes a 1-byte NULL out-of-bounds write on the dynamically allocated seq buffer. Fix this by checking for overflow immediately after seq_printf().

Quoted source text, attributed separately from HOL analysis.