CVE-2026-43035 net: sched: cls_api: fix tc_chain_fill_node to initialize tcm_info to zero to prevent an info-leak
A local attacker can read uninitialized kernel heap memory via netlink messages, potentially exposing sensitive data.
- 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-2026-43035?
CVE-2026-43035 is a medium-severity 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:
net: sched: cls_api: fix tc_chain_fill_node to initialize tcm_info to zero to prevent an info-leak
When building netlink messages, tc_chain_fill_node() never initializes the tcm_info field of struct tcmsg. Since the allocation is not zeroed, kernel heap memory is leaked to userspace through this 4-byte field.
The fix simply zeroes tcm_info alongside the other fields that are already initialized.
Weakness: CWE-908
Which versions are affected by CVE-2026-43035?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43035?
Apply the vendor's patch.
Is CVE-2026-43035 being exploited?
There is no known exploitation of CVE-2026-43035 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-43035, DEBIAN-CVE-2026-43035, GHSA-w7cv-frw4-84fj, ROOT-OS-DEBIAN-11-CVE-2026-43035, ROOT-OS-UBUNTU-2204-CVE-2026-43035, ROOT-OS-UBUNTU-2404-CVE-2026-43035 and 1 more.