CVE-2026-53267netfilter: nft_ct: bail out on template ct in get eval
- 7.8HighCVSS base score
- 0.12%Exploitation in 30 daysEPSS · top 98% 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: 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
Timeline
ID reserved
By Linux
- 16 days later
· 16 days later
Published
- 4 months later
· 4 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 |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.12% · top 98% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Affected products
- affected 45d9bcda21f4c13be75e3571b0f0ef39e77934b5 – < 15bf8091f424f97ed8bfd2385f9fca3203f27be2
- affected 45d9bcda21f4c13be75e3571b0f0ef39e77934b5 – < af80f78ce984649e1698b841cd33f4fa505ad828
- affected 45d9bcda21f4c13be75e3571b0f0ef39e77934b5 – < 8470f676eadeab99132708acb1a85915664d6115
- affected 45d9bcda21f4c13be75e3571b0f0ef39e77934b5 – < f071b0bf078146368d18e4eec386bf2ddc0ab7e0
- affected 45d9bcda21f4c13be75e3571b0f0ef39e77934b5 – < 2e154b5f53f1b0b490c7b8b02499f90feb86b1d5
- affected 45d9bcda21f4c13be75e3571b0f0ef39e77934b5 – < 3027ecbdb5fdf9200251c21d4818e4c447ef78e1
- affected 4.1
- unaffected < 4.1
- unaffected 6.1.191 – ≤ 6.1.*
- unaffected 6.6.143 – ≤ 6.6.*
- unaffected 6.12.94 – ≤ 6.12.*
- unaffected 6.18.36 – ≤ 6.18.*
- unaffected 7.0.13 – ≤ 7.0.*
- unaffected 7.1 – ≤ *
References
References6
- https://git.kernel.org/stable/c/15bf8091f424f97ed8bfd2385f9fca3203f27be2 (opens in a new tab)
- https://git.kernel.org/stable/c/af80f78ce984649e1698b841cd33f4fa505ad828 (opens in a new tab)
- https://git.kernel.org/stable/c/8470f676eadeab99132708acb1a85915664d6115 (opens in a new tab)
- https://git.kernel.org/stable/c/f071b0bf078146368d18e4eec386bf2ddc0ab7e0 (opens in a new tab)
- https://git.kernel.org/stable/c/2e154b5f53f1b0b490c7b8b02499f90feb86b1d5 (opens in a new tab)
- https://git.kernel.org/stable/c/3027ecbdb5fdf9200251c21d4818e4c447ef78e1 (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-2026-39218 (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-2026-53267)Record last updated .