CVE-2026-52919 batman-adv: fix tp_meter counter underflow during shutdown
A counter underflow in the batman-adv kernel module causes a use-after-free, allowing attackers to execute code or crash the system.
- 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-2026-52919?
CVE-2026-52919 is a high-severity use after free vulnerability in Linux kernel, published on 24 Jun 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:
batman-adv: fix tp_meter counter underflow during shutdown
batadv_tp_sender_shutdown() unconditionally decrements the "sending" atomic counter. If multiple paths (e.g. timeout, user cancel, and normal finish) call this function, the counter can underflow to -1.
Since the sender logic treats any non-zero value as "still sending", a negative value causes the sender kthread to loop indefinitely. This leads to a use-after-free when the interface is removed while the zombie thread is still active.
Fix this by using atomic_xchg() to ensure the counter only transitions from 1 to 0 once.
[sven: added missing change in batadv_tp_send]
Weakness: CWE-191
Which versions are affected by CVE-2026-52919?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-52919?
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-2026-52919 being exploited?
There is no known exploitation of CVE-2026-52919 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-90338, BELL-CVE-2026-52919, DEBIAN-CVE-2026-52919, GHSA-428c-jvg5-r285, ROOT-OS-DEBIAN-11-CVE-2026-52919, ROOT-OS-DEBIAN-12-CVE-2026-52919 and 3 more.