block: don't overwrite bip_vcnt in bio_integrity_copy_user() (CVE-2026-64053) | HOL Guard CVE

High · CVSS 7.8CVE-2026-64053

block: don't overwrite bip_vcnt in bio_integrity_copy_user()

Answer in brief

CVE-2026-64053 records a High severity (CVSS 7.8) vulnerability in block: don't overwrite bip_vcnt in bio_integrity_copy_user(). 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 2, 2026Source checked Sep 20, 2026First seen by HOL Aug 5, 2026Material review Sep 2, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.8
Exploitation: Not marked as known exploited
Affected software: 6 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

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=3991657ae7074c3c497bf095093178bed37ea1b4 <d18160c9525c63c203656fefd847e94b538cd4a4 \|\| >=3991657ae7074c3c497bf095093178bed37ea1b4 <0d48654af4d1390c888389206cc13b51b82c30e6 \|\| >=3991657ae7074c3c497bf095093178bed37ea1b4 <066be1439593a381b1a29663becfcfe0c92363e7 \|\| >=3991657ae7074c3c497bf095093178bed37ea1b4 <637ad3a56a3b889527d1dacea6fea2a8bd648140	d18160c9525c63c203656fefd847e94b538cd4a4, 0d48654af4d1390c888389206cc13b51b82c30e6, 066be1439593a381b1a29663becfcfe0c92363e7, 637ad3a56a3b889527d1dacea6fea2a8bd648140
Linux/Linuxgeneric	6.11	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to d18160c9525c63c203656fefd847e94b538cd4a4 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 2, 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: block: don't overwrite bip_vcnt in bio_integrity_copy_user() bio_integrity_add_page() already sets bip_vcnt to 1 for the bounce segment. Overwriting it with nr_vecs breaks bip_vcnt <= bip_max_vcnt on WRITE (bip_max_vcnt is 1), so the gap-merge checks in block/blk.h read past the bip_vec[] flex array. On READ the read is in bounds but lands on a saved user bvec instead of the bounce. The line was added for split propagation, but bio_integrity_clone() doesn't copy bip_vcnt and BIP_CLONE_FLAGS excludes BIP_COPY_USER.

Quoted source text, attributed separately from HOL analysis.