Answer in brief
CVE-2026-46063 records a Unknown severity vulnerability in x86/shstk: Prevent deadlock during shstk sigreturn. 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.
A CVSS score is not reported in the current record. 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.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=7fad2a432cd35bbf104d2d9d426e74902f22aa95 <e2c2b044458cbf22da05264fa707308e8d4f86f9 || >=7fad2a432cd35bbf104d2d9d426e74902f22aa95 <d042d69b417515959e49021fef008c9b04a99bd5 || >=7fad2a432cd35bbf104d2d9d426e74902f22aa95 <4f3374c990fb2adec06d20fd6d780927811c9aa0 || >=7fad2a432cd35bbf104d2d9d426e74902f22aa95 <3d29db827502067626062f5c74dd502d14ab15bc || >=7fad2a432cd35bbf104d2d9d426e74902f22aa95 <9874b2917b9fbc30956fee209d3c4aa47201c64e | e2c2b044458cbf22da05264fa707308e8d4f86f9, d042d69b417515959e49021fef008c9b04a99bd5, 4f3374c990fb2adec06d20fd6d780927811c9aa0, 3d29db827502067626062f5c74dd502d14ab15bc, 9874b2917b9fbc30956fee209d3c4aa47201c64e |
| Linux/Linuxgeneric | 6.6 | Not reported |
Published upstream
May 27, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 6, 2026
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.
Quoted source text, attributed separately from HOL analysis.