{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-53267", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-06-09T07:44:35.395Z", "datePublished": "2026-06-25T08:39:53.852Z", "dateUpdated": "2026-08-05T12:34:44.447Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:34:44.447Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nft_ct: bail out on template ct in get eval\n\nI noticed this issue while looking at a historic syzbot report [1].\n\nA rule like the one below is enough to trigger the bug:\n\n table ip t {\n chain pre {\n type filter hook prerouting priority raw;\n ct zone set 1\n ct original saddr 1.2.3.4 accept\n }\n }\n\nThe first expression attaches a per-cpu template ct via\nnft_ct_set_zone_eval() (nf_ct_tmpl_alloc -> kzalloc, tuple is all\nzero, nf_ct_l3num(ct) == 0). The next expression then calls\nnft_ct_get_eval() on the same skb, treats the template as a real ct\nand hits the 16-byte memcpy path. With dreg at NFT_REG32_15 this\noverflows past struct nft_regs on the kernel stack; with smaller\ndreg values it silently clobbers adjacent registers.\n\nReject template ct at the eval entry and in nft_ct_get_fast_eval(),\nmirroring the check nft_ct_set_eval() already has. Additionally,\nbound the address copy in NFT_CT_SRC / NFT_CT_DST by priv->len\ninstead of by nf_ct_l3num(ct): nf_ct_get_tuple() zeroes the tuple\nbefore pkt_to_tuple() fills in only the protocol-relevant leading\nbytes, so the trailing bytes of tuple->{src,dst}.u3.all are\nwell-defined zero. priv->len is validated at rule load, so the\ncopy size is now bounded by the destination register rather than\nby an untrusted field on the conntrack.\n\n[1]: https://syzkaller.appspot.com/bug?id=389cf09cb72926114fce90dc85a2c3231dcb647c" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable code is reached by installing crafted nftables/netfilter rules through NETLINK_NETFILTER and then triggering packet evaluation locally. Remote packets alone cannot install the rule, so this is a local attack vector.\nAC:L - A single crafted rule sequence such as `ct zone set` followed by `ct original saddr` can deterministically trigger the bug on matching packets. No race or external condition beyond the attacker's control is required.\nPR:L - Rule creation requires CAP_NET_ADMIN for the relevant network namespace via nfnetlink. Because nftables is reachable with CAP_NET_ADMIN in a user-created network namespace on systems permitting unprivileged user namespaces, this is low privileges rather than high.\nUI:N - After the attacker installs the crafted rule, triggering occurs through packet processing without any victim user action. No user needs to open a file, mount anything, or interact with attacker-controlled content.\nS:U - The bug corrupts kernel memory during kernel packet-filter evaluation and impacts the same kernel security authority. This is standard kernel privilege escalation/DoS behavior, not a VM, IOMMU, or distinct security-scope escape.\nC:H - The bug is a kernel stack out-of-bounds write past `struct nft_regs`, a memory corruption primitive. Under the required higher-severity rule, such memory corruption is defensibly treated as capable of enabling high confidentiality impact.\nI:H - The vulnerable 16-byte memcpy can overwrite beyond the validated destination register on the kernel stack. Out-of-bounds kernel writes are high integrity impact because they can plausibly be developed into control-flow or privilege-modification primitives.\nA:H - The stack overwrite can corrupt adjacent stack state or registers during packet evaluation and can crash or oops the kernel. Kernel crash or panic is high availability impact." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/netfilter/nft_ct.c", "net/netfilter/nft_ct_fast.c" ], "versions": [ { "version": "45d9bcda21f4c13be75e3571b0f0ef39e77934b5", "lessThan": "af80f78ce984649e1698b841cd33f4fa505ad828", "status": "affected", "versionType": "git" }, { "version": "45d9bcda21f4c13be75e3571b0f0ef39e77934b5", "lessThan": "8470f676eadeab99132708acb1a85915664d6115", "status": "affected", "versionType": "git" }, { "version": "45d9bcda21f4c13be75e3571b0f0ef39e77934b5", "lessThan": "f071b0bf078146368d18e4eec386bf2ddc0ab7e0", "status": "affected", "versionType": "git" }, { "version": "45d9bcda21f4c13be75e3571b0f0ef39e77934b5", "lessThan": "2e154b5f53f1b0b490c7b8b02499f90feb86b1d5", "status": "affected", "versionType": "git" }, { "version": "45d9bcda21f4c13be75e3571b0f0ef39e77934b5", "lessThan": "3027ecbdb5fdf9200251c21d4818e4c447ef78e1", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/netfilter/nft_ct.c", "net/netfilter/nft_ct_fast.c" ], "versions": [ { "version": "4.1", "status": "affected" }, { "version": "0", "lessThan": "4.1", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.143", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.94", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.36", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.13", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "6.6.143" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "6.12.94" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "6.18.36" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "7.0.13" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/af80f78ce984649e1698b841cd33f4fa505ad828" }, { "url": "https://git.kernel.org/stable/c/8470f676eadeab99132708acb1a85915664d6115" }, { "url": "https://git.kernel.org/stable/c/f071b0bf078146368d18e4eec386bf2ddc0ab7e0" }, { "url": "https://git.kernel.org/stable/c/2e154b5f53f1b0b490c7b8b02499f90feb86b1d5" }, { "url": "https://git.kernel.org/stable/c/3027ecbdb5fdf9200251c21d4818e4c447ef78e1" } ], "title": "netfilter: nft_ct: bail out on template ct in get eval", "x_generator": { "engine": "bippy-1.2.0" } } } }