CVE-2026-53134 netfilter: nft_fib: fix stale stack leak via the OIFNAME register
A local attacker can leak uninitialized kernel stack memory to userspace via the netfilter nft_fib module's OIFNAME register handling.
- 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-2026-53134?
CVE-2026-53134 is a medium-severity vulnerability in Linux kernel, published on 25 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:
netfilter: nft_fib: fix stale stack leak via the OIFNAME register
For NFT_FIB_RESULT_OIFNAME the destination register is declared with len = IFNAMSIZ (four 32-bit registers), but on the lookup-fail, RTN_LOCAL and oif-mismatch paths nft_fib{4,6}_eval() only writes one register via "*dest = 0". The remaining three registers are left as whatever was on the stack in nft_do_chain()'s struct nft_regs, and a downstream expression that loads the register span can leak that uninitialised kernel stack to userspace.
The NFTA_FIB_F_PRESENT existence check has the same shape: it is only meaningful for NFT_FIB_RESULT_OIF, yet it was accepted for any result type while the eval stores a single byte via nft_reg_store8(), leaving the rest of the declared span stale.
Fix both:
- replace the bare "*dest = 0" in the eval with nft_fib_store_result(), which strscpy_pad()s the whole IFNAMSIZ for OIFNAME (and is already used on the other early-return path), and
- restrict NFTA_FIB_F_PRESENT to NFT_FIB_RESULT_OIF and declare its destination as a single u8, so the marked span matches the one byte the eval writes.
Weakness: CWE-401
Which versions are affected by CVE-2026-53134?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-53134?
Apply the vendor's patch.
Is CVE-2026-53134 being exploited?
There is no known exploitation of CVE-2026-53134 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as AZL-90527, BELL-CVE-2026-53134, DEBIAN-CVE-2026-53134, GHSA-5wp9-x843-xmxf, ROOT-OS-DEBIAN-11-CVE-2026-53134, ROOT-OS-DEBIAN-12-CVE-2026-53134 and 3 more.