EXPLOIT/ALERT Back to feed

Linux vulnerability

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.

Published 25 Jun 2026Updated 8 Sep 20269 sources
CVSS 5.5
Overview Sources History

What happened

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.

Affected versions

Linux: f6d0cbcf09c506b9b022df8f9d7693a7cec3c732 through before 6744e49fe51bfba26522acc2d0e9703cb41d8e50 (git); f6d0cbcf09c506b9b022df8f9d7693a7cec3c732 through before eca18feed38b3377a2ec5d1f22af1170c55d0171 (git); f6d0cbcf09c506b9b022df8f9d7693a7cec3c732 through before d19ddef8c327a4773ff81f8e51027d1e0b4cf069 (git); f6d0cbcf09c506b9b022df8f9d7693a7cec3c732 through before eb8a8124484dbc3c2b543e207da39bbccb703d31 (git); f6d0cbcf09c506b9b022df8f9d7693a7cec3c732 through before 8c84885e9790823828bb8084736ea15769b1ac16 (git); f6d0cbcf09c506b9b022df8f9d7693a7cec3c732 through before 84d8f58cf28a0415413f43ba7148f7bacd4c1b6e (git); f6d0cbcf09c506b9b022df8f9d7693a7cec3c732 through before 3544210609f6d1db282bbdeca639104ef624c393 (git); f6d0cbcf09c506b9b022df8f9d7693a7cec3c732 through before ab185e0c4fb82dfba6fb86f8271e06f931d9c64c (git); 4.10; V3.1.6 through before * (custom) Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

  • Apply vendor-provided updates or mitigations.
  • Review affected product exposure and access logs.

Public PoC references

No public PoC reference has passed the current publication threshold.

CorrectionsReport an issue