CVE-2026-43020 Bluetooth: MGMT: validate LTK enc_size on load
A stack buffer overflow in the Linux kernel Bluetooth subsystem allows attackers to execute arbitrary code or escalate privileges via oversized encryption key sizes.
- 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-2026-43020?
CVE-2026-43020 is a high-severity memory corruption vulnerability in Linux kernel, published on 1 May 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:
Bluetooth: MGMT: validate LTK enc_size on load
Load Long Term Keys stores the user-provided enc_size and later uses it to size fixed-size stack operations when replying to LE LTK requests. An enc_size larger than the 16-byte key buffer can therefore overflow the reply stack buffer.
Reject oversized enc_size values while validating the management LTK record so invalid keys never reach the stored key state.
Weakness: CWE-787
Which versions are affected by CVE-2026-43020?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43020?
Apply the vendor's patch.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-43020 being exploited?
There is no known exploitation of CVE-2026-43020 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43020, DEBIAN-CVE-2026-43020, GHSA-4qqh-3j35-gpcq, ROOT-OS-DEBIAN-11-CVE-2026-43020, ROOT-OS-UBUNTU-2204-CVE-2026-43020, ROOT-OS-UBUNTU-2404-CVE-2026-43020 and 1 more.