CVE-2026-93167: Linux Vulnerability

Description

In the Linux kernel, the following vulnerability has been resolved: csky: Fix a4/a5 restoration in syscall trace path The syscall trace path reloads syscall arguments from pt_regs before calling the syscall handler. On C-SKY ABIv2, the 5th and 6th syscall arguments are prepared as stack arguments before invoking syscallid. The current code adjusts sp before loading LSAVE_A4 and LSAVE_A5. Since those offsets are relative to the original pt_regs base, loading them after changing sp fetches the wrong slots. As a result, traced syscalls that use the 5th or 6th argument may receive corrupted arguments. This is visible with mmap2(), which takes six arguments. A small PTRACE_SYSCALL reproducer opens a file and maps one page with: mmap(NULL, 4096, PROT_READ | PROT_EXEC, MAP_PRIVATE, fd, 0) Before the fix, the traced child fails the mmap and exits with 12. After the fix, the mapping succeeds and the child exits with 0. Fix the trace path by loading a4/a5 from pt_regs before changing sp. Tested on: ck860f, linux-4.19.15, C-SKY abiv2

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= e0bbb53843b5fdfe464b099217e3b9d97e8a75d7, < e9ae8e86eed68bea5d2670eadf61938a43bd2263; >= e0bbb53843b5fdfe464b099217e3b9d97e8a75d7, < 64e3ec7a71d3b715e2567f19f64207f04999bb0c; >= e0bbb53843b5fdfe464b099217e3b9d97e8a75d7, < 863fa63fd1491f201ac819f805a8db98d2a32c3d; >= e0bbb53843b5fdfe464b099217e3b9d97e8a75d7, < e71a3dc5b8d2ea4d9cfbdb135d6b7777de84212e; >= e0bbb53843b5fdfe464b099217e3b9d97e8a75d7, < 31c81b376e5f058c7f2c94f69719cf7caec2fc3f; >= e0bbb53843b5fdfe464b099217e3b9d97e8a75d7, < a776afa89424570bfa637ebf812ca281a5732904; >= e0bbb53843b5fdfe464b099217e3b9d97e8a75d7, < 343aa5275484d627c921a42e8e115cae366be5de; >= e0bbb53843b5fdfe464b099217e3b9d97e8a75d7, < abb81e5ce7d995baa41556b8125fa59e28ba3be8; 108681048cf728a8570e036c34ebd7daa43133b4; 3a5837c692918c229baf63fe7950965d27c48ac2; >= 5.4.47, < 5.5; >= 5.6.19, < 5.7
Linux	Linux	5.7

References

Timeline

Published: Sep 17, 2026
Last Modified: Sep 17, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-93167?

In the Linux kernel, the following vulnerability has been resolved: csky: Fix a4/a5 restoration in syscall trace path The syscall trace path reloads syscall arguments from pt_regs before calling the syscall handler. On C-SKY ABIv2, the 5th and 6th syscall arguments are prepared as stack arguments before invoking syscallid. The current code adjusts sp before loading LSAVE_A4 and LSAVE_A5. Since those offsets are relative to the original pt_regs base, loading them after changing sp fetches the wrong slots. As a result, traced syscalls that use the 5th or 6th argument may receive corrupted arguments. This is visible with mmap2(), which takes six arguments. A small PTRACE_SYSCALL reproducer opens a file and maps one page with: mmap(NULL, 4096, PROT_READ | PROT_EXEC, MAP_PRIVATE, fd, 0) Before the fix, the traced child fails the mmap and exits with 12. After the fix, the mapping succeeds and the child exits with 0. Fix the trace path by loading a4/a5 from pt_regs before changing sp. Tested on: ck860f, linux-4.19.15, C-SKY abiv2

How severe is CVE-2026-93167?

Severity scoring for CVE-2026-93167 is pending analysis.

How do I fix CVE-2026-93167?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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