CVE-2026-43026netfilter: ctnetlink: zero expect NAT fields when CTA_EXPECT_NAT absent
- 5.5MediumCVSS base score
- 0.13%Exploitation in 30 daysEPSS · top 97% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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
ID reserved
By Linux
Published
- 6 months later
· 6 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Medium5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.13% · top 97% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.
Affected products
- affected 076a0ca02644657b13e4af363f487ced2942e9cb – < a5a89db6981a1ddf2314bf50cb49db5a3146185f
- affected 076a0ca02644657b13e4af363f487ced2942e9cb – < 1c2ebdeff8d088a2e47ae25d7b38447249adace2
- affected 076a0ca02644657b13e4af363f487ced2942e9cb – < a64b7bf84b4d5ea54218c5d374ec87fff9000f43
- affected 076a0ca02644657b13e4af363f487ced2942e9cb – < 2898080c054ea4d6ddfaaf21bbedbc229a9a8376
- affected 076a0ca02644657b13e4af363f487ced2942e9cb – < fd002ff2ea030cbfb0188a11b3c60ce7f84485f4
- affected 076a0ca02644657b13e4af363f487ced2942e9cb – < 929f7a9a7aad9404a5867216c3f8738232355b38
- affected 076a0ca02644657b13e4af363f487ced2942e9cb – < bff0f4f06f12d6d9bc565a3e1378abd4f6f5ce36
- affected 076a0ca02644657b13e4af363f487ced2942e9cb – < 35177c6877134a21315f37d57a5577846225623e
- affected 3.4
- unaffected < 3.4
- unaffected 5.10.253 – ≤ 5.10.*
- unaffected 5.15.203 – ≤ 5.15.*
- unaffected 6.1.168 – ≤ 6.1.*
- unaffected 6.6.134 – ≤ 6.6.*
- unaffected 6.12.81 – ≤ 6.12.*
- unaffected 6.18.22 – ≤ 6.18.*
- unaffected 6.19.12 – ≤ 6.19.*
- unaffected 7.0 – ≤ *
References
References11
- https://git.kernel.org/stable/c/a5a89db6981a1ddf2314bf50cb49db5a3146185f (opens in a new tab)
- https://git.kernel.org/stable/c/1c2ebdeff8d088a2e47ae25d7b38447249adace2 (opens in a new tab)
- https://git.kernel.org/stable/c/a64b7bf84b4d5ea54218c5d374ec87fff9000f43 (opens in a new tab)
- https://git.kernel.org/stable/c/2898080c054ea4d6ddfaaf21bbedbc229a9a8376 (opens in a new tab)
- https://git.kernel.org/stable/c/fd002ff2ea030cbfb0188a11b3c60ce7f84485f4 (opens in a new tab)
- https://git.kernel.org/stable/c/929f7a9a7aad9404a5867216c3f8738232355b38 (opens in a new tab)
- https://git.kernel.org/stable/c/bff0f4f06f12d6d9bc565a3e1378abd4f6f5ce36 (opens in a new tab)
- https://git.kernel.org/stable/c/35177c6877134a21315f37d57a5577846225623e (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-26625 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-43026)Record last updated .