Bluetooth: ISO: fix race of kfree vs kref_get_unless_zero (CVE-2026-74533) | HOL Guard CVE

High · CVSS 8.8CVE-2026-74533

Bluetooth: ISO: fix race of kfree vs kref_get_unless_zero

Answer in brief

CVE-2026-74533 records a High severity (CVSS 8.8) vulnerability in Bluetooth: ISO: fix race of kfree vs kref_get_unless_zero. 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 Aug 15, 2026Updated Aug 17, 2026Source checked Sep 29, 2026First seen by HOL Aug 15, 2026Material review Aug 17, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 8.8
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

CVSS is 8.8. 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.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=dc26097bdb864a0d5955b9a25e43376ffc1af99b <876a3e94c70d0859d1dad1c986112d4f0d99eba8 \|\| >=dc26097bdb864a0d5955b9a25e43376ffc1af99b <af24e338bf5dafb80f42baa9a0b9e9b57b1c5d9c \|\| f53e7489273dc2bb307bf50f319b3762d45534f0 \|\| a58d0f5dac322e16cc75334d000666512341bde5 \|\| >=6.11.11 <6.12 \|\| >=6.12.2 <6.13	876a3e94c70d0859d1dad1c986112d4f0d99eba8, af24e338bf5dafb80f42baa9a0b9e9b57b1c5d9c, 6.12, 6.13
Linux/Linuxgeneric	6.13	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 876a3e94c70d0859d1dad1c986112d4f0d99eba8 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 15, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 15, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: ISO: fix race of kfree vs kref_get_unless_zero hci_conn::iso_data is accessed and modified without lock or RCU. This leads to a race [Task hdev->workqueue] [Task 2] iso_recv iso_conn_put(conn) conn = LOAD hcon->iso_data iso_conn_free(conn) iso_conn_hold_unless_zero(conn) hcon->iso_data = NULL kfree(conn) kref_get_unless_zero(&conn->ref) /* UAF */ and also to races in iso_conn_add() vs. iso_conn_free(). Fix by adding spinlock hci_conn::proto_lock and using it to guard hci_conn::iso_data.

Quoted source text, attributed separately from HOL analysis.