CVE-2026-53267netfilter: nft_ct: bail out on template ct in get eval
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_ct: bail out on template ct in get eval I noticed this issue while looking at a historic syzbot report [1]. A rule like the one below is enough to trigger the bug: table ip t { chain pre { type filter hook prerouting priority raw; ct zone set 1 ct original saddr 1.2.3.4 accept } } The first expression attaches a per-cpu template ct via nft_ct_set_zone_eval() (nf_ct_tmpl_alloc -> kzalloc, tuple is all zero, nf_ct_l3num(ct) == 0). The next expression then calls nft_ct_get_eval() on the same skb, treats the template as a real ct and hits the 16-byte memcpy path. With dreg at NFT_REG32_15 this overflows past struct nft_regs on the kernel stack; with smaller dreg values it silently clobbers adjacent registers. Reject template ct at the eval entry and in nft_ct_get_fast_eval(), mirroring the check nft_ct_set_eval() already has. Additionally, bound the address copy in NFT_CT_SRC / NFT_CT_DST by priv->len instead of by nf_ct_l3num(ct): nf_ct_get_tuple() zeroes the tuple before pkt_to_tuple() fills in only the protocol-relevant leading bytes, so the trailing bytes of tuple->{src,dst}.u3.all are well-defined zero. priv->len is validated at rule load, so the copy size is now bounded by the destination register rather than by an untrusted field on the conntrack. [1]: https://syzkaller.appspot.com/bug?id=389cf09cb72926114fce90dc85a2c3231dcb647c
- CVSS
- 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Analyzed
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 45d9bcda21f4c13be75e3571b0f0ef39e77934b5 before af80f78ce984649e1698b841cd33f4fa505ad828; from 45d9bcda21f4c13be75e3571b0f0ef39e77934b5 before 8470f676eadeab99132708acb1a85915664d6115; from 45d9bcda21f4c13be75e3571b0f0ef39e77934b5 before f071b0bf078146368d18e4eec386bf2ddc0ab7e0; 45d9bcda21f4c13be75e3571b0f0ef39e77934b5 builds before 2e154b5f53f1b0b490c7b8b02499f90feb86b1d5; from 45d9bcda21f4c13be75e3571b0f0ef39e77934b5 before 3027ecbdb5fdf9200251c21d4818e4c447ef78e1 | CNA record |
linux linux_kernel linux:linux_kernel | from 4.1 before 6.6.143; from 6.7 before 6.12.94; from 6.13 before 6.18.36; from 6.19 before 7.0.13; 7.1; 7.1; 7.1; 7.1; and 2 more ranges | NVD |
References
- https://git.kernel.org/stable/c/af80f78ce984649e1698b841cd33f4fa505ad828patch
- https://git.kernel.org/stable/c/8470f676eadeab99132708acb1a85915664d6115patch
- https://git.kernel.org/stable/c/f071b0bf078146368d18e4eec386bf2ddc0ab7e0patch
- https://git.kernel.org/stable/c/2e154b5f53f1b0b490c7b8b02499f90feb86b1d5patch
- https://git.kernel.org/stable/c/3027ecbdb5fdf9200251c21d4818e4c447ef78e1patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.