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CVE-2026-46063— x86/shstk: Prevent deadlock during shstk sigreturn

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于x86/shstk中影子栈信号返回时持有mmap读锁可能导致死锁。以下版本受到影响：修复版本之前版本。

AI Predicted 7.8 Difficulty: Hard EPSS 0.09% · P1

Affected Version Matrix 12

VendorProduct Version RangeStatus
Linux Linux 7fad2a432cd35bbf104d2d9d426e74902f22aa95< e2c2b044458cbf22da05264fa707308e8d4f86f9 affected
7fad2a432cd35bbf104d2d9d426e74902f22aa95< d042d69b417515959e49021fef008c9b04a99bd5 affected
7fad2a432cd35bbf104d2d9d426e74902f22aa95< 4f3374c990fb2adec06d20fd6d780927811c9aa0 affected
7fad2a432cd35bbf104d2d9d426e74902f22aa95< 3d29db827502067626062f5c74dd502d14ab15bc affected
7fad2a432cd35bbf104d2d9d426e74902f22aa95< 9874b2917b9fbc30956fee209d3c4aa47201c64e affected
6.6 affected
< 6.6 unaffected
6.6.140≤ 6.6.* unaffected
… +4 more rows
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I. Basic Information for CVE-2026-46063

Vulnerability Information
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Vulnerability Title
x86/shstk: Prevent deadlock during shstk sigreturn
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: x86/shstk: Prevent deadlock during shstk sigreturn During sigreturn the shadow stack signal frame is popped. The kernel does this by reading the shadow stack using normal read accesses. When it can't assume the memory is shadow stack, it takes extra steps to makes sure it is reading actual shadow stack memory and not other normal readable memory. It does this by holding the mmap read lock while doing the access and checking the flags of the VMA. Unfortunately that is not safe. If the read of the shadow stack sigframe hits a page fault, the fault handler will try to recursively grab another mmap read lock. This normally works ok, but if a writer on another CPU is also waiting, the second read lock could fail and cause a deadlock. Fix this by not holding mmap lock during the read access to userspace. Instead use mmap_lock_speculate_...() to watch for changes between dropping mmap lock and the userspace access. Retry if anything grabbed an mmap write lock in between and could have changed the VMA. These mmap_lock_speculate_...() helpers use mm::mm_lock_seq, which is only available when PER_VMA_LOCK is configured. So make X86_USER_SHADOW_STACK depend on it. On x86, PER_VMA_LOCK is a default configuration for SMP kernels. So drop support for the other configs under the assumption that the !SMP shadow stack user base does not exist. Currently there is a check that skips the lookup work when the SSP can be assumed to be on a shadow stack. While reorganizing the function, remove the optimization to make the tricky code flows more common, such that issues like this cannot escape detection for so long.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel存在安全漏洞，该漏洞源于x86/shstk中影子栈信号返回时持有mmap读锁可能导致死锁。以下版本受到影响：修复版本之前版本。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 7fad2a432cd35bbf104d2d9d426e74902f22aa95 ~ e2c2b044458cbf22da05264fa707308e8d4f86f9 -
Linux Linux 6.6 -

II. Public POCs for CVE-2026-46063

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III. Intelligence Information for CVE-2026-46063

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Patches & Fixes for CVE-2026-46063 (5)

Same Patch Batch · Linux · 2026-05-27 · 275 CVEs total

CVE-2026-45898 9.8 CRITICAL RDMA/iwcm: Fix workqueue list corruption by removing work_list
CVE-2026-46039 9.8 CRITICAL rxgk: Fix potential integer overflow in length check
CVE-2026-45988 9.8 CRITICAL rxrpc: Fix re-decryption of RESPONSE packets
CVE-2026-45972 9.8 CRITICAL smb: client: fix potential UAF and double free in smb2_open_file()
CVE-2026-46043 9.1 CRITICAL RDMA/rxe: Validate pad and ICRC before payload_size() in rxe_rcv
CVE-2026-45945 8.8 HIGH iommu/vt-d: Fix race condition during PASID entry replacement
CVE-2026-46056 8.8 HIGH Bluetooth: hci_event: fix potential UAF in SSP passkey handlers
CVE-2026-45843 8.2 HIGH slip: bound decode() reads against the compressed packet length
CVE-2025-71311 8.2 HIGH fs/ntfs3: Initialize new folios before use
CVE-2026-46037 8.2 HIGH ipv4: icmp: validate reply type before using icmp_pointers
CVE-2026-46010 8.1 HIGH rxrpc: Fix error handling in rxgk_extract_token()
CVE-2026-46099 8.1 HIGH net: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels
CVE-2026-46076 7.9 HIGH KVM: nSVM: Raise #UD if unhandled VMMCALL isn't intercepted by L1
CVE-2026-45935 7.8 HIGH fs/ntfs3: Fix slab-out-of-bounds read in DeleteIndexEntryRoot
CVE-2026-46058 7.8 HIGH media: amphion: Fix race between m2m job_abort and device_run
CVE-2026-46065 7.8 HIGH fbdev: defio: Disconnect deferred I/O from the lifetime of struct fb_info
CVE-2026-45909 7.8 HIGH clk: mediatek: Drop __initconst from gates
CVE-2026-45959 7.8 HIGH crypto: ccp - Fix a crash due to incorrect cleanup usage of kfree
CVE-2026-45931 7.8 HIGH accel/amdxdna: Hold mm structure across iommu_sva_unbind_device()
CVE-2026-46015 7.8 HIGH tcp: call sk_data_ready() after listener migration

Showing top 20 of 275 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-46063

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