CVE-2026-98888 arm64: kprobes: Allow reentering kprobes while single-stepping
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-98888?
CVE-2026-98888 is a vulnerability in Linux, published on 23 Oct 2026.
Official description
In the Linux kernel, the following vulnerability has been resolved:
arm64: kprobes: Allow reentering kprobes while single-stepping
A kprobe can be hit while another kprobe is in KPROBE_HIT_SS state. This can happen when tracing or perf code runs from the debug exception path while the first kprobe is preparing or executing its out-of-line single-step instruction.
Currently arm64 treats a kprobe hit in KPROBE_HIT_SS as unrecoverable, the same as a hit in KPROBE_REENTER. This is too strict. A hit in KPROBE_HIT_SS is still a one-level reentry and can be handled by saving the current kprobe state and setting up single-step for the new probe, just like reentry from KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE.
The truly unrecoverable case is hitting another kprobe while already in KPROBE_REENTER, because the reentry save area has already been consumed.
Move KPROBE_HIT_SS to the recoverable reentry cases and leave KPROBE_REENTER as the unrecoverable nested reentry case.
This change also requires saving saved_irqflag in struct prev_kprobe. When a nested kprobe calls kprobes_save_local_irqflag(), it overwrites kcb->saved_irqflag with the currently masked DAIF value, losing the outer kprobe's original DAIF state. Without this fix, when the outer kprobe's single-step finishes, kprobes_restore_local_irqflag() applies the wrong DAIF mask and leaves interrupts permanently disabled.
Extend struct prev_kprobe with a saved_irqflag field and save/restore it alongside kp and status. This ensures the outer kprobe's original interrupt state is preserved across reentry.
This mirrors the x86 fix in commit 6a5022a56ac3 ("kprobes/x86: Allow to handle reentered kprobe on single-stepping").
Which versions are affected by CVE-2026-98888?
How do I fix CVE-2026-98888?
Upgrade to a fixed version.
Is CVE-2026-98888 being exploited?
There is no known exploitation of CVE-2026-98888 in the wild and no public exploit code.
Sources
Also known as AZL-110629, BELL-CVE-2026-98888, DEBIAN-CVE-2026-98888, GHSA-g4px-h95h-7mgm, UBUNTU-CVE-2026-98888.