CVE-2026-89440 mmc: via-sdmmc: stop card-detect handling on probe failure
A use-after-free vulnerability in the Linux kernel's via-sdmmc driver allows attackers to cause denial of service or execute code via improper interrupt handling on probe failure.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-89440?
CVE-2026-89440 is a high-severity use after free vulnerability in Linux, published on 11 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:
mmc: via-sdmmc: stop card-detect handling on probe failure
request_irq() registers the SD card-detect interrupt and the probe enables it before mmc_add_host() runs. If mmc_add_host() fails, the error path only unmaps the registers and returns: the interrupt stays registered, so the handler keeps running against the host once it is freed. via_sdc_isr() dereferences sdhost and its MMIO base and schedules carddet_work, which via_sdc_card_detect() also runs against freed memory through its container_of() dereference.
Add a probe-error path that disables and frees the interrupt and cancels carddet_work before unmapping. carddet_work can re-enable the device interrupt via via_reset_pcictrl(), which restores PCIINTCTRL, so mask it again after cancelling the work.
This issue was found by an in-house static analysis tool and confirmed by manual code review.
Which versions are affected by CVE-2026-89440?
How do I fix CVE-2026-89440?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-89440 being exploited?
There is no known exploitation of CVE-2026-89440 in the wild and no public exploit code.
Sources
Also known as AZL-100836, BELL-CVE-2026-89440, DEBIAN-CVE-2026-89440, GHSA-g7ff-3gj4-4wp3, UBUNTU-CVE-2026-89440.