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:
- Cryptographic API;
- ACPI drivers;
- HSI subsystem;
- I3C subsystem;
- InfiniBand drivers;
- Media drivers;
- Network drivers;
- Pin controllers subsystem;
- AFS file system;
- F2FS file system;
- SMB network file system;
- Padata parallel execution mechanism;
- Timer subsystem;
- Tracing infrastructure;
- Memory management;
- Appletalk network protocol;
- Networking core;
- Netfilter;
(CVE-2022-49026, CVE-2022-49390, CVE-2023-52854, CVE-2024-35867,
CVE-2024-47691, CVE-2024-49935, CVE-2024-50061, CVE-2024-50067,
CVE-2024-50095, CVE-2024-50196, CVE-2024-53090, CVE-2024-53218,
CVE-2024-56664, CVE-2025-21727, CVE-2025-21855, CVE-2025-37838,
CVE-2025-37958, CVE-2025-38352, CVE-2025-38666, CVE-2025-39964,
CVE-2025-39993, CVE-2025-40018)
Fixed packages 2
| Release | Package | Fixed in |
|---|---|---|
| Ubuntu · Pro 18.04 LTS Pro:18.04:LTS | linux-azure-5.4 | 5.4.0-1156.163~18.04.1 |
| Ubuntu · Pro 20.04 LTS Pro:20.04:LTS | linux-azure | 5.4.0-1156.163 |
Vulnerabilities 23
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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
crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg
In the Linux kernel, the following vulnerability has been resolved: crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg Issuing two writes to the same af_alg socket is bogus as the data will be interleaved in an unpredictable fashion. Furthermore, c…
KEV Sep 18, 2026 -
High 8.6
ibmvnic: Don't reference skb after sending to VIOS
In the Linux kernel, the following vulnerability has been resolved: ibmvnic: Don't reference skb after sending to VIOS Previously, after successfully flushing the xmit buffer to VIOS, the tx_bytes stat was incremented by the length of the skb. It is invalid t…
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High 7.8
e100: Fix possible use after free in e100_xmit_prepare
In the Linux kernel, the following vulnerability has been resolved: e100: Fix possible use after free in e100_xmit_prepare In e100_xmit_prepare(), if we can't map the skb, then return -ENOMEM, so e100_xmit_frame() will return NETDEV_TX_BUSY and the upper laye…
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High 7.8
macsec: fix UAF bug for real_dev
In the Linux kernel, the following vulnerability has been resolved: macsec: fix UAF bug for real_dev Create a new macsec device but not get reference to real_dev. That can not ensure that real_dev is freed after macsec. That will trigger the UAF bug for real_…
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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.
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High 7.8
uprobe: avoid out-of-bounds memory access of fetching args
In the Linux kernel, the following vulnerability has been resolved: uprobe: avoid out-of-bounds memory access of fetching args Uprobe needs to fetch args into a percpu buffer, and then copy to ring buffer to avoid non-atomic context problem. Sometimes user-sp…
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High 7.8
f2fs: fix race in concurrent f2fs_stop_gc_thread
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix race in concurrent f2fs_stop_gc_thread In my test case, concurrent calls to f2fs shutdown report the following stack trace: Oops: general protection fault, probably for non-canonica…
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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…
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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…
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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…
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High 7.8
media: rc: fix races with imon_disconnect()
In the Linux kernel, the following vulnerability has been resolved: media: rc: fix races with imon_disconnect() Syzbot reports a KASAN issue as below: BUG: KASAN: use-after-free in __create_pipe include/linux/usb.h:1945 [inline] BUG: KASAN: use-after-free in …
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High 7.8
ipvs: Defer ip_vs_ftp unregister during netns cleanup
In the Linux kernel, the following vulnerability has been resolved: ipvs: Defer ip_vs_ftp unregister during netns cleanup On the netns cleanup path, __ip_vs_ftp_exit() may unregister ip_vs_ftp before connections with valid cp->app pointers are flushed, leadin…
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High 7.5
RDMA/mad: Improve handling of timed out WRs of mad agent
In the Linux kernel, the following vulnerability has been resolved: RDMA/mad: Improve handling of timed out WRs of mad agent Current timeout handler of mad agent acquires/releases mad_agent_priv lock for every timed out WRs. This causes heavy locking contenti…
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High 7.5
afs: Fix lock recursion
In the Linux kernel, the following vulnerability has been resolved: afs: Fix lock recursion afs_wake_up_async_call() can incur lock recursion. The problem is that it is called from AF_RXRPC whilst holding the ->notify_lock, but it tries to take a ref on the a…
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Medium 5.5
pinctrl: ocelot: fix system hang on level based interrupts
In the Linux kernel, the following vulnerability has been resolved: pinctrl: ocelot: fix system hang on level based interrupts The current implementation only calls chained_irq_enter() and chained_irq_exit() if it detects pending interrupts. ``` for (i = 0; i…
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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 …
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Unscored —
f2fs: fix to avoid use-after-free in f2fs_stop_gc_thread()
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to avoid use-after-free in f2fs_stop_gc_thread() syzbot reports a f2fs bug as below: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 print_…
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Unscored —
ACPI: PAD: fix crash in exit_round_robin()
In the Linux kernel, the following vulnerability has been resolved: ACPI: PAD: fix crash in exit_round_robin() The kernel occasionally crashes in cpumask_clear_cpu(), which is called within exit_round_robin(), because when executing clear_bit(nr, addr) with n…
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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…
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Unscored —
mm/huge_memory: fix dereferencing invalid pmd migration entry
In the Linux kernel, the following vulnerability has been resolved: mm/huge_memory: fix dereferencing invalid pmd migration entry When migrating a THP, concurrent access to the PMD migration entry during a deferred split scan can lead to an invalid address ac…
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Unscored —
net: appletalk: Fix use-after-free in AARP proxy probe
In the Linux kernel, the following vulnerability has been resolved: net: appletalk: Fix use-after-free in AARP proxy probe The AARP proxy‐probe routine (aarp_proxy_probe_network) sends a probe, releases the aarp_lock, sleeps, then re-acquires the lock. During…
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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-2022-49026
-
report
https://ubuntu.com/security/CVE-2022-49390
-
report
https://ubuntu.com/security/CVE-2023-52854
-
report
https://ubuntu.com/security/CVE-2024-35867
-
report
https://ubuntu.com/security/CVE-2024-47691
-
report
https://ubuntu.com/security/CVE-2024-49935
-
report
https://ubuntu.com/security/CVE-2024-50061
-
report
https://ubuntu.com/security/CVE-2024-50067
-
report
https://ubuntu.com/security/CVE-2024-50095
-
report
https://ubuntu.com/security/CVE-2024-50196
-
report
https://ubuntu.com/security/CVE-2024-53090
-
report
https://ubuntu.com/security/CVE-2024-53218
-
report
https://ubuntu.com/security/CVE-2024-56664
-
report
https://ubuntu.com/security/CVE-2025-21727
-
report
https://ubuntu.com/security/CVE-2025-21855
-
report
https://ubuntu.com/security/CVE-2025-37838
-
report
https://ubuntu.com/security/CVE-2025-37958
-
report
https://ubuntu.com/security/CVE-2025-38352
-
report
https://ubuntu.com/security/CVE-2025-38666
-
report
https://ubuntu.com/security/CVE-2025-39964
-
report
https://ubuntu.com/security/CVE-2025-39993
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report
https://ubuntu.com/security/CVE-2025-40018
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report
https://ubuntu.com/security/CVE-2025-40300