CVE-2026-93182 sched/fair: Fix overflow in update_tg_cfs_runnable()
An integer overflow in the Linux kernel scheduler can lead to a divide-by-zero crash, causing a local 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-2026-93182?
CVE-2026-93182 is a vulnerability in Linux, published on 17 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:
sched/fair: Fix overflow in update_tg_cfs_runnable()
A divide-by-zero crash is observed when running hackbench:
[14697.488452] CPU: 112 UID: 0 PID: 124791 Comm: hackbench Not tainted 7.1.0-rc2+ [14697.492627] RIP: 0010:propagate_entity_load_avg+0x35f/0x3e0 [14697.506799] <TASK> [14697.507411] __dequeue_task+0x2b4/0xc70 [14697.508677] dequeue_task_fair+0x36/0x370 [14697.509047] dequeue_task+0x101/0x2f0 [14697.509426] __schedule+0x1b1/0x1a00 [14697.510868] anon_pipe_read+0x3da/0x450 [14697.511400] vfs_read+0x361/0x390 [14697.512053] __x64_sys_read+0x19/0x30
The divide-by-zero happens here:
if (scale_load_down(gcfs_rq->load.weight)) { load_sum = div_u64(gcfs_rq->avg.load_sum, scale_load_down(gcfs_rq->load.weight)); }
gcfs_rq->load.weight is an insane large value and is truncated to the lower 32 bits by div_u64, which happen to be 0.
Using AI for investigation, the cause is a u32 overflow in update_tg_cfs_runnable(), and flat pickup became a victim when using tg_tasks():
u32 new_sum, divider; ... new_sum = se->avg.runnable_avg * divider; <-- boom
The following sequence shows how this triggers the crash:
propagate_entity_load_avg() update_tg_cfs_runnable() # u32 overflow corrupts runnable_sum
__update_load_avg_cfs_rq() ___update_load_avg() # computes insane runnable_avg update_tg_load_avg() # propagates to tg->runnable_avg
update_cfs_group() calc_concur_shares() tg_tasks() # long-to-int truncation, negative nr reweight_entity() # corrupted se->load.weight update_load_add() # corrupted cfs_rq->load.weight
propagate_entity_load_avg() update_tg_cfs_load() div_u64() # divide-by-zero
Fix by widening new_sum from u32 to u64 (no need to force tg_tasks() to return unsigned long after this fix)
Which versions are affected by CVE-2026-93182?
How do I fix CVE-2026-93182?
Apply the vendor's patch.
Is CVE-2026-93182 being exploited?
There is no known exploitation of CVE-2026-93182 in the wild and no public exploit code.
Sources
Also known as AZL-102744, BELL-CVE-2026-93182, DEBIAN-CVE-2026-93182, GHSA-8vpp-69hw-pqmm, UBUNTU-CVE-2026-93182.