Bluetooth: ISO: fix race of kfree vs kref_get_unless_zero
CVE-2026-74533 · published 15 Aug 2026
How serious is it
- Severity: high, CVSS score 8.8 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-74533?
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Who is affected
- Linux Linux: a58d0f5dac322e16cc75334d000666512341bde5 to < 08ac98f18c8d24cc037858dd6fba2670155e4e84, dc26097bdb864a0d5955b9a25e43376ffc1af99b to < 876a3e94c70d0859d1dad1c986112d4f0d99eba8, dc26097bdb864a0d5955b9a25e43376ffc1af99b to < af24e338bf5dafb80f42baa9a0b9e9b57b1c5d9c, f53e7489273dc2bb307bf50f319b3762d45534f0
- Linux Linux: 6.13
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
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.
Check your whole app
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References
- git.kernel.org/stable/c/08ac98f18c8d24cc037858dd6fba2670155e4e84
- git.kernel.org/stable/c/876a3e94c70d0859d1dad1c986112d4f0d99eba8
- git.kernel.org/stable/c/af24e338bf5dafb80f42baa9a0b9e9b57b1c5d9c
Merged from CVE List. Last updated 25 Oct 2026. All vulnerabilities · RSS · JSON