CVE-2026-53134

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

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://git.kernel.org/stable/c/3544210609f6d1db282bbdeca639104ef624c393
• https://git.kernel.org/stable/c/6744e49fe51bfba26522acc2d0e9703cb41d8e50
• https://git.kernel.org/stable/c/84d8f58cf28a0415413f43ba7148f7bacd4c1b6e
• https://git.kernel.org/stable/c/8c84885e9790823828bb8084736ea15769b1ac16
• https://git.kernel.org/stable/c/ab185e0c4fb82dfba6fb86f8271e06f931d9c64c
• https://git.kernel.org/stable/c/d19ddef8c327a4773ff81f8e51027d1e0b4cf069
• https://git.kernel.org/stable/c/eb8a8124484dbc3c2b543e207da39bbccb703d31
• https://git.kernel.org/stable/c/eca18feed38b3377a2ec5d1f22af1170c55d0171