{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-64007", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.026Z", "datePublished": "2026-07-19T14:56:23.049Z", "dateUpdated": "2026-07-19T14:56:23.049Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-07-19T14:56:23.049Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: synproxy: refresh tcphdr after skb_ensure_writable\n\nsynproxy_tstamp_adjust() rewrites the TCP timestamp option in place\nand then patches the TCP checksum via inet_proto_csum_replace4() on\nthe caller-supplied tcphdr pointer. Both ipv4_synproxy_hook() and\nipv6_synproxy_hook() obtain that pointer with skb_header_pointer()\nbefore calling in, so it may either alias skb->head directly or\npoint at the caller's on-stack _tcph buffer.\n\nBetween obtaining the pointer and using it, the function calls\nskb_ensure_writable(skb, optend), which on a cloned or non-linear\nskb invokes pskb_expand_head() and frees the old skb->head. After\nthat point the cached th is stale:\n\n caller (ipv[46]_synproxy_hook)\n th = skb_header_pointer(skb, ..., &_tcph)\n synproxy_tstamp_adjust(skb, protoff, th, ...)\n skb_ensure_writable(skb, optend)\n pskb_expand_head() /* kfree(old skb->head) */\n ...\n inet_proto_csum_replace4(&th->check, ...)\n /* writes into freed head, or\n into the caller's stack copy\n leaving the on-wire checksum\n stale */\n\nThe option bytes are written through skb->data and are fine; only\nthe checksum update goes through th and so lands in the wrong\nplace. The result is either a write into freed slab memory or a\npacket leaving with a checksum that does not match its payload.\n\nFix by re-deriving th from skb->data + protoff immediately after\nskb_ensure_writable() succeeds, so the subsequent checksum update\ntargets the linear, writable header."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/netfilter/nf_synproxy_core.c"], "versions": [{"version": "48b1de4c110a7afa4b85862f6c75af817db26fad", "lessThan": "9902a1058992de5d95656b64a3bd95c077f7ba2c", "status": "affected", "versionType": "git"}, {"version": "48b1de4c110a7afa4b85862f6c75af817db26fad", "lessThan": "d3019c61799adc21811af4b521f11f3dc77f8e04", "status": "affected", "versionType": "git"}, {"version": "48b1de4c110a7afa4b85862f6c75af817db26fad", "lessThan": "dd206819f210522579010d889d45a9530bb494bc", "status": "affected", "versionType": "git"}, {"version": "48b1de4c110a7afa4b85862f6c75af817db26fad", "lessThan": "af2c22ccb1f621aff487ff47a040e38e058541e7", "status": "affected", "versionType": "git"}, {"version": "48b1de4c110a7afa4b85862f6c75af817db26fad", "lessThan": "c7f945f7da097245a2f8ed7775ce48421047ee96", "status": "affected", "versionType": "git"}, {"version": "48b1de4c110a7afa4b85862f6c75af817db26fad", "lessThan": "f0fea2b6d5453a11ad11713bbf37561b9b3a7edf", "status": "affected", "versionType": "git"}, {"version": "48b1de4c110a7afa4b85862f6c75af817db26fad", "lessThan": "a91887a5b6ee4b98dfbf1db657ed2b879430149e", "status": "affected", "versionType": "git"}, {"version": "48b1de4c110a7afa4b85862f6c75af817db26fad", "lessThan": "92170e6afe927ab2792a3f71902845789c8e31b1", "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/nf_synproxy_core.c"], "versions": [{"version": "3.12", "status": "affected"}, {"version": "0", "lessThan": "3.12", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.259", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.210", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.176", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.143", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.93", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.35", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.0.12", "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": "3.12", "versionEndExcluding": "5.10.259"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.12", "versionEndExcluding": "5.15.210"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.12", "versionEndExcluding": "6.1.176"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.12", "versionEndExcluding": "6.6.143"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.12", "versionEndExcluding": "6.12.93"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.12", "versionEndExcluding": "6.18.35"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.12", "versionEndExcluding": "7.0.12"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.12", "versionEndExcluding": "7.1"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/9902a1058992de5d95656b64a3bd95c077f7ba2c"}, {"url": "https://git.kernel.org/stable/c/d3019c61799adc21811af4b521f11f3dc77f8e04"}, {"url": "https://git.kernel.org/stable/c/dd206819f210522579010d889d45a9530bb494bc"}, {"url": "https://git.kernel.org/stable/c/af2c22ccb1f621aff487ff47a040e38e058541e7"}, {"url": "https://git.kernel.org/stable/c/c7f945f7da097245a2f8ed7775ce48421047ee96"}, {"url": "https://git.kernel.org/stable/c/f0fea2b6d5453a11ad11713bbf37561b9b3a7edf"}, {"url": "https://git.kernel.org/stable/c/a91887a5b6ee4b98dfbf1db657ed2b879430149e"}, {"url": "https://git.kernel.org/stable/c/92170e6afe927ab2792a3f71902845789c8e31b1"}], "title": "netfilter: synproxy: refresh tcphdr after skb_ensure_writable", "x_generator": {"engine": "bippy-1.2.0"}}}}

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