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CVE-2026-43026

netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.253, 5.15.203, 6.1.168, 6.6.134, 6.12.81, and 2 more
None on Exploit-DB, Metasploit or GitHub

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent ctnetlink_alloc_expect() allocates expectations from a non-zeroing slab cache via nf_ct_expect_alloc(). When CTA_EXPECT_NAT is not present in the netlink message, saved_addr and saved_proto are never initialized. Stale data from a previous slab occupant can then be dumped to userspace by ctnetlink_exp_dump_expect(), which checks these fields to decide whether to emit CTA_EXPECT_NAT. The safe sibling nf_ct_expect_init(), used by the packet path, explicitly zeroes these fields. Zero saved_addr, saved_proto and dir in the else branch, guarded by IS_ENABLED(CONFIG_NF_NAT) since these fields only exist when NAT is enabled. Confirmed by priming the expect slab with NAT-bearing expectations, freeing them, creating a new expectation without CTA_EXPECT_NAT, and observing that the ctnetlink dump emits a spurious CTA_EXPECT_NAT containing stale data from the prior allocation.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From 076a0ca02644657b13e4af363f487ced2942e9cb · fixed in a5a89db6981a1ddf2314bf50cb49db5a3146185f; From 076a0ca02644657b13e4af363f487ced2942e9cb · fixed in 1c2ebdeff8d088a2e47ae25d7b38447249adace2; From 076a0ca02644657b13e4af363f487ced2942e9cb · fixed in a64b7bf84b4d5ea54218c5d374ec87fff9000f43; From 076a0ca02644657b13e4af363f487ced2942e9cb · fixed in 2898080c054ea4d6ddfaaf21bbedbc229a9a8376; From 076a0ca02644657b13e4af363f487ced2942e9cb · fixed in fd002ff2ea030cbfb0188a11b3c60ce7f84485f4; From 076a0ca02644657b13e4af363f487ced2942e9cb · fixed in 929f7a9a7aad9404a5867216c3f8738232355b38; From 076a0ca02644657b13e4af363f487ced2942e9cb · fixed in bff0f4f06f12d6d9bc565a3e1378abd4f6f5ce36; From 076a0ca02644657b13e4af363f487ced2942e9cb · fixed in 35177c6877134a21315f37d57a5577846225623e

  • Linux Linux

    3.4

  • KernelLinux

    From 3.4.0 · fixed in 5.10.253; From 5.11.0 · fixed in 5.15.203; From 5.16.0 · fixed in 6.1.168; From 6.2.0 · fixed in 6.6.134; From 6.7.0 · fixed in 6.12.81; From 6.13.0 · fixed in 6.18.22; From 6.19.0 · fixed in 6.19.12

References 8

git.kernel.org