CVE-2026-93240 memcg: make the v1 soft limit knob inert
A kernel bug in memory cgroup soft limit handling could cause a warning or instability when triggered by privileged users, requiring a patch to stabilize the system.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-93240?
CVE-2026-93240 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:
memcg: make the v1 soft limit knob inert
The v1 soft limit has been deprecated since v6.12 and nobody has reported depending on it. Start the removal by decoupling the interface from the implementation: keep memory.soft_limit_in_bytes, but ignore writes to it and always report the maximum value on read similar to what memory.kmem.limit_in_bytes already does.
Writes are still parsed, so malformed input keeps returning -EINVAL. The knob now also behaves the same everywhere: it used to return -EOPNOTSUPP on PREEMPT_RT, where soft limit reclaim has always been disabled.
This also fixes the syzbot report linked below. Soft limit reclaim is the only caller that runs shrink_lruvec() from kswapd against a specific memcg, so it is the only way to reach lru_gen_shrink_lruvec() and in turn set_mm_walk(), which warns when called from kswapd.
Which versions are affected by CVE-2026-93240?
How do I fix CVE-2026-93240?
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-2026-93240 being exploited?
There is no known exploitation of CVE-2026-93240 in the wild and no public exploit code.
Sources
Also known as AZL-103559, BELL-CVE-2026-93240, DEBIAN-CVE-2026-93240, GHSA-xfgg-2xcm-vrc8, UBUNTU-CVE-2026-93240.