CVE-2026-97515 i3c: master: svc: Prevent IRQ storm from false SLVSTART on NPCM845
A hardware quirk in the NPCM845 I3C driver causes an infinite interrupt loop, leading to CPU lockup and denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-97515?
CVE-2026-97515 is a denial of service vulnerability in Linux, published on 24 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
i3c: master: svc: Prevent IRQ storm from false SLVSTART on NPCM845
On NPCM845, when a target on the I3C bus gets stuck holding SDA low, the controller reports a false Master Request (MR) in-band interrupt event. The driver handles this by emitting a STOP condition to restore the bus.
However, the hardware quirk SVC_I3C_QUIRK_FALSE_SLVSTART indicates that emitting a STOP condition may spuriously set the SLVSTART interrupt status bit. In the Master Request case, this creates a feedback loop: the STOP triggers a new SLVSTART event, the IRQ handler fires again, the controller still reports an MR type, another STOP is emitted, and the cycle repeats indefinitely, resulting in an IRQ storm that can lock up the CPU.
Clear the SLVSTART status bit explicitly after emitting the STOP in the Master Request IBI handler when the SVC_I3C_QUIRK_FALSE_SLVSTART quirk is set. This breaks the feedback loop without affecting normal SLVSTART processing, which is already guarded in the top-level IRQ handler by checking that MSTATUS is in SLVREQ state.
Which versions are affected by CVE-2026-97515?
How do I fix CVE-2026-97515?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-97515 being exploited?
There is no known exploitation of CVE-2026-97515 in the wild and no public exploit code.
Sources
Also known as AZL-103820, BELL-CVE-2026-97515, DEBIAN-CVE-2026-97515, GHSA-jcmj-p262-2c6x, UBUNTU-CVE-2026-97515.