CVE-2026-74376 md/raid10: reset read_slot when reusing r10bio for discard
A use-after-free vulnerability in the Linux kernel's RAID10 driver allows attackers to cause denial of service or potentially execute code via crafted discard operations.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74376?
CVE-2026-74376 is a critical use after free vulnerability in Linux, published on 15 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
md/raid10: reset read_slot when reusing r10bio for discard
put_all_bios() always drops devs[i].bio, but it only drops devs[i].repl_bio when r10_bio->read_slot < 0. If discard reuses an r10bio that was previously used for a read, read_slot can still be non-negative, and discard cleanup can skip bio_put() on repl_bio.
Reset read_slot to -1 when preparing an r10bio for discard so the replacement bio is always released correctly.
Which versions are affected by CVE-2026-74376?
How do I fix CVE-2026-74376?
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-2026-74376 being exploited?
There is no known exploitation of CVE-2026-74376 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74376, DEBIAN-CVE-2026-74376, GHSA-4w7v-gf5r-fhph, UBUNTU-CVE-2026-74376.