CVE-2026-53267
netfilter: nft_ct: bail out on template ct in get eval
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
INFO
Published Date :
June 25, 2026, 9:16 a.m.
Last Modified :
July 8, 2026, 4:01 a.m.
Remotely Exploit :
No
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
- Apply the fix to the Linux kernel netfilter module.
- Ensure nft_ct template ct is rejected at eval.
- Bound address copy by destination register size.
- Update kernel to include the fix.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-53267.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-53267 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-53267
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-53267 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-53267 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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Initial Analysis by [email protected]
Jul. 08, 2026
Action Type Old Value New Value Added CWE CWE-674 Added CPE Configuration OR *cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.18.36 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 up to (excluding) 6.12.94 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.19 up to (excluding) 7.0.13 *cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc6:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 4.1 up to (excluding) 6.6.143 Added Reference Type kernel.org: https://git.kernel.org/stable/c/2e154b5f53f1b0b490c7b8b02499f90feb86b1d5 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/3027ecbdb5fdf9200251c21d4818e4c447ef78e1 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/8470f676eadeab99132708acb1a85915664d6115 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/af80f78ce984649e1698b841cd33f4fa505ad828 Types: Patch Added Reference Type kernel.org: https://git.kernel.org/stable/c/f071b0bf078146368d18e4eec386bf2ddc0ab7e0 Types: Patch -
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jun. 28, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Jun. 25, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '45d9bcda21f4c13be75e3571b0f0ef39e77934b5', 'lessThan': 'af80f78ce984649e1698b841cd33f4fa505ad828', 'versionType': 'git'}, {'status': 'affected', 'version': '45d9bcda21f4c13be75e3571b0f0ef39e77934b5', 'lessThan': '8470f676eadeab99132708acb1a85915664d6115', 'versionType': 'git'}, {'status': 'affected', 'version': '45d9bcda21f4c13be75e3571b0f0ef39e77934b5', 'lessThan': 'f071b0bf078146368d18e4eec386bf2ddc0ab7e0', 'versionType': 'git'}, {'status': 'affected', 'version': '45d9bcda21f4c13be75e3571b0f0ef39e77934b5', 'lessThan': '2e154b5f53f1b0b490c7b8b02499f90feb86b1d5', 'versionType': 'git'}, {'status': 'affected', 'version': '45d9bcda21f4c13be75e3571b0f0ef39e77934b5', 'lessThan': '3027ecbdb5fdf9200251c21d4818e4c447ef78e1', 'versionType': 'git'}], 'programFiles': ['net/netfilter/nft_ct.c', 'net/netfilter/nft_ct_fast.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '4.1'}, {'status': 'unaffected', 'version': '0', 'lessThan': '4.1', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '6.6.143', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.94', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.36', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.0.13', 'versionType': 'semver', 'lessThanOrEqual': '7.0.*'}, {'status': 'unaffected', 'version': '7.1', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['net/netfilter/nft_ct.c', 'net/netfilter/nft_ct_fast.c'], 'defaultStatus': 'affected'}] Added 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 Added Reference https://git.kernel.org/stable/c/2e154b5f53f1b0b490c7b8b02499f90feb86b1d5 Added Reference https://git.kernel.org/stable/c/3027ecbdb5fdf9200251c21d4818e4c447ef78e1 Added Reference https://git.kernel.org/stable/c/8470f676eadeab99132708acb1a85915664d6115 Added Reference https://git.kernel.org/stable/c/af80f78ce984649e1698b841cd33f4fa505ad828 Added Reference https://git.kernel.org/stable/c/f071b0bf078146368d18e4eec386bf2ddc0ab7e0