Summary
Jean-Claude Graf, Sandro Rüegge, Ali Hajiabadi, and Kaveh Razavi discovered
that the Linux kernel contained insufficient branch predictor isolation
between a guest and a userspace hypervisor for certain processors. This
flaw is known as VMSCAPE. An attacker in a guest VM could possibly use this
to expose sensitive information from the host OS. (CVE-2025-40300)
Several security issues were discovered in the Linux kernel.
An attacker could possibly use these to compromise the system.
This update corrects flaws in the following subsystems:
- HSI subsystem;
- I3C subsystem;
- SMB network file system;
- Padata parallel execution mechanism;
- Timer subsystem;
- Networking core;
(CVE-2023-52854, CVE-2024-35867, CVE-2024-50061, CVE-2024-56664,
CVE-2025-21727, CVE-2025-37838, CVE-2025-38352)
Fixed packages 1
| Release | Package | Fixed in |
|---|---|---|
| Ubuntu · Pro 20.04 LTS Pro:20.04:LTS | linux-iot | 5.4.0-1056.59 |
Vulnerabilities 8
-
High 7.8
posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del()
In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del() If an exiting non-autoreaping task has already passed exit_notify() and calls handle_posix_cpu_timers() …
KEV Sep 4, 2025 -
High 7.8
smb: client: fix potential UAF in cifs_stats_proc_show()
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix potential UAF in cifs_stats_proc_show() Skip sessions that are being teared down (status == SES_EXITING) to avoid UAF.
-
High 7.8
bpf, sockmap: Fix race between element replace and close()
In the Linux kernel, the following vulnerability has been resolved: bpf, sockmap: Fix race between element replace and close() Element replace (with a socket different from the one stored) may race with socket's close() link popping & unlinking. __sock_map_de…
-
High 7.8
padata: fix UAF in padata_reorder
In the Linux kernel, the following vulnerability has been resolved: padata: fix UAF in padata_reorder A bug was found when run ltp test: BUG: KASAN: slab-use-after-free in padata_find_next+0x29/0x1a0 Read of size 4 at addr ffff88bbfe003524 by task kworker/u11…
-
High 7.8
HSI: ssi_protocol: Fix use after free vulnerability in ssi_protocol Driver Due to Race Condition
In the Linux kernel, the following vulnerability has been resolved: HSI: ssi_protocol: Fix use after free vulnerability in ssi_protocol Driver Due to Race Condition In the ssi_protocol_probe() function, &ssi->work is bound with ssip_xmit_work(), In ssip_pn_se…
-
Unscored —
padata: Fix refcnt handling in padata_free_shell()
In the Linux kernel, the following vulnerability has been resolved: padata: Fix refcnt handling in padata_free_shell() In a high-load arm64 environment, the pcrypt_aead01 test in LTP can lead to system UAF (Use-After-Free) issues. Due to the lengthy analysis …
-
Unscored —
i3c: master: cdns: Fix use after free vulnerability in cdns_i3c_master Driver Due to Race Condition
In the Linux kernel, the following vulnerability has been resolved: i3c: master: cdns: Fix use after free vulnerability in cdns_i3c_master Driver Due to Race Condition In the cdns_i3c_master_probe function, &master->hj_work is bound with cdns_i3c_master_hj. A…
-
Unscored —
x86/vmscape: Add conditional IBPB mitigation
In the Linux kernel, the following vulnerability has been resolved: x86/vmscape: Add conditional IBPB mitigation VMSCAPE is a vulnerability that exploits insufficient branch predictor isolation between a guest and a userspace hypervisor (like QEMU). Existing …
References
-
report
https://ubuntu.com/security/CVE-2023-52854
-
report
https://ubuntu.com/security/CVE-2024-35867
-
report
https://ubuntu.com/security/CVE-2024-50061
-
report
https://ubuntu.com/security/CVE-2024-56664
-
report
https://ubuntu.com/security/CVE-2025-21727
-
report
https://ubuntu.com/security/CVE-2025-37838
-
report
https://ubuntu.com/security/CVE-2025-38352
-
report
https://ubuntu.com/security/CVE-2025-40300