CVE-2026-64422 (GCVE-0-2026-64422)
Vulnerability from cvelistv5
Published
2026-07-25 08:51
Modified
2026-10-19 20:38
Severity ?
7.1 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes Reject invalid `net.ipv4.tcp_reordering` values before they reach TCP socket state. The sysctl is stored as an `int` but copied into the `u32` `tp->reordering` field for new sockets, so negative writes wrap to large values. With `tcp_mtu_probing=2`, the wrapped value can overflow the `tcp_mtu_probe()` size calculation and drive the MTU probing path into an out-of-bounds read. Route `tcp_reordering` writes through `proc_dointvec_minmax()` and require it to be at least 1. Also require `tcp_max_reordering` to be at least 1 so the configured maximum cannot become negative either. When registering the table for a non-init network namespace, relocate `extra2` pointers that refer into `init_net.ipv4` so the `tcp_reordering` upper bound follows that namespace's `tcp_max_reordering`. Harden `tcp_mtu_probe()` itself by computing `size_needed` as `u64`. This keeps the send queue and window checks from being bypassed through signed integer overflow.
References
Impacted products
Vendor Product Version
Linux Linux Version: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf
Version: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf
Version: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf
Version: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf
Version: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf
Version: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf
Version: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf
Version: 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf
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remote packets alone cannot introduce the invalid signed value.\\nAC:L - The attacker can set both tcp_reordering and tcp_mtu_probing=2, establish an attacker-controlled TCP connection, grow its congestion window, and control queued data and receiver-window conditions.\\nPR:L - Writes require CAP_NET_ADMIN in the network namespace\\u2019s owning user namespace, which an unprivileged user can obtain by creating user and network namespaces on systems permitting unprivileged user namespaces.\\nUI:N - The attacker can configure the namespace and trigger MTU probing using their own TCP endpoints without any victim action.\\nS:U - The vulnerable TCP implementation and the affected kernel memory and availability remain within the Linux kernel\\u2019s security authority.\\nC:H - The overflow bypasses send-queue validation and causes an out-of-bounds kernel-memory read through an invalid skb traversal, potentially exposing sensitive kernel data.\\nI:N - The established primitive is an out-of-bounds read and malformed skb state; the affected path provides no demonstrated out-of-bounds write or other data-modification primitive.\\nA:H - The invalid skb access and inconsistent payload geometry can cause an OOPS, BUG, or kernel panic, and an attacker can trigger the path repeatedly.\"}]}], \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"91cc17c0e5e5ada156a8d5787a2509d263ea6bbf\", \"lessThan\": \"f0d88a4cd03affff6c08adf6c63964e235aede43\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"91cc17c0e5e5ada156a8d5787a2509d263ea6bbf\", \"lessThan\": \"27ddf4486c7dbf5bdd393fa8bef6b67179796d98\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"91cc17c0e5e5ada156a8d5787a2509d263ea6bbf\", \"lessThan\": \"782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"91cc17c0e5e5ada156a8d5787a2509d263ea6bbf\", \"lessThan\": \"e81f805824a8109504fce090641b17d135b48cd1\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"91cc17c0e5e5ada156a8d5787a2509d263ea6bbf\", \"lessThan\": \"99206ce2244f8a3ed64298d0667c9055845a5dc7\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"91cc17c0e5e5ada156a8d5787a2509d263ea6bbf\", \"lessThan\": \"bbae351c0f32f7c200249e4aa6561b2b419dcf69\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"91cc17c0e5e5ada156a8d5787a2509d263ea6bbf\", \"lessThan\": \"a094ac95d3b69adfa1676eb9c8eae6835d4f1671\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"91cc17c0e5e5ada156a8d5787a2509d263ea6bbf\", \"lessThan\": \"efb8763d7bbb40cff4cc55a6b62c3095a038149c\", \"versionType\": \"git\"}], \"programFiles\": [\"net/ipv4/sysctl_net_ipv4.c\", \"net/ipv4/tcp_output.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"2.6.24\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"2.6.24\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"5.10.261\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.10.*\"}, {\"status\": \"unaffected\", \"version\": \"5.15.212\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.15.*\"}, {\"status\": \"unaffected\", \"version\": \"6.1.178\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.1.*\"}, {\"status\": \"unaffected\", \"version\": \"6.6.145\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.6.*\"}, {\"status\": \"unaffected\", \"version\": \"6.12.96\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.12.*\"}, {\"status\": \"unaffected\", \"version\": \"6.18.39\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.18.*\"}, {\"status\": \"unaffected\", \"version\": \"7.1.4\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"7.1.*\"}, {\"status\": \"unaffected\", \"version\": \"7.2\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"net/ipv4/sysctl_net_ipv4.c\", \"net/ipv4/tcp_output.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/f0d88a4cd03affff6c08adf6c63964e235aede43\"}, {\"url\": \"https://git.kernel.org/stable/c/27ddf4486c7dbf5bdd393fa8bef6b67179796d98\"}, {\"url\": \"https://git.kernel.org/stable/c/782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae\"}, {\"url\": \"https://git.kernel.org/stable/c/e81f805824a8109504fce090641b17d135b48cd1\"}, {\"url\": \"https://git.kernel.org/stable/c/99206ce2244f8a3ed64298d0667c9055845a5dc7\"}, {\"url\": \"https://git.kernel.org/stable/c/bbae351c0f32f7c200249e4aa6561b2b419dcf69\"}, {\"url\": \"https://git.kernel.org/stable/c/a094ac95d3b69adfa1676eb9c8eae6835d4f1671\"}, {\"url\": \"https://git.kernel.org/stable/c/efb8763d7bbb40cff4cc55a6b62c3095a038149c\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nnet: ipv4: bound TCP reordering sysctl writes and MTU probe sizes\\n\\nReject invalid `net.ipv4.tcp_reordering` values before they reach TCP\\nsocket state. The sysctl is stored as an `int` but copied into the\\n`u32` `tp-\u003ereordering` field for new sockets, so negative writes wrap\\nto large values.\\n\\nWith `tcp_mtu_probing=2`, the wrapped value can overflow the\\n`tcp_mtu_probe()` size calculation and drive the MTU probing path into\\nan out-of-bounds read. Route `tcp_reordering` writes through\\n`proc_dointvec_minmax()` and require it to be at least 1. Also require\\n`tcp_max_reordering` to be at least 1 so the configured maximum cannot\\nbecome negative either.\\n\\nWhen registering the table for a non-init network namespace, relocate\\n`extra2` pointers that refer into `init_net.ipv4` so the\\n`tcp_reordering` upper bound follows that namespace\u0027s\\n`tcp_max_reordering`.\\n\\nHarden `tcp_mtu_probe()` itself by computing `size_needed` as `u64`.\\nThis keeps the send queue and window checks from being bypassed through\\nsigned integer overflow.\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.10.261\", \"versionStartIncluding\": \"2.6.24\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.15.212\", \"versionStartIncluding\": \"2.6.24\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.1.178\", \"versionStartIncluding\": \"2.6.24\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.6.145\", \"versionStartIncluding\": \"2.6.24\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.12.96\", \"versionStartIncluding\": \"2.6.24\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.18.39\", \"versionStartIncluding\": \"2.6.24\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.1.4\", \"versionStartIncluding\": \"2.6.24\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.2\", \"versionStartIncluding\": \"2.6.24\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-17T04:55:22.159Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-64422\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-10-19T20:38:28.132Z\", \"dateReserved\": \"2026-07-19T15:36:31.787Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2026-07-25T08:51:00.671Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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