net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-64422
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-25 10:17:26 UTC
Updated2026-07-27 05:16:48 UTC
DescriptionIn 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.

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

EPSS: 0.001320000 probability, percentile 0.031450000 (date 2026-07-27)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.1HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
3.1CNADECLARED7.1HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf f0d88a4cd03affff6c08adf6c63964e235aede43 git Not specified
CNA Linux Linux affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf 27ddf4486c7dbf5bdd393fa8bef6b67179796d98 git Not specified
CNA Linux Linux affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf 782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae git Not specified
CNA Linux Linux affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf e81f805824a8109504fce090641b17d135b48cd1 git Not specified
CNA Linux Linux affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf 99206ce2244f8a3ed64298d0667c9055845a5dc7 git Not specified
CNA Linux Linux affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf bbae351c0f32f7c200249e4aa6561b2b419dcf69 git Not specified
CNA Linux Linux affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf a094ac95d3b69adfa1676eb9c8eae6835d4f1671 git Not specified
CNA Linux Linux affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf efb8763d7bbb40cff4cc55a6b62c3095a038149c git Not specified
CNA Linux Linux affected 2.6.24 Not specified
CNA Linux Linux unaffected 2.6.24 semver Not specified
CNA Linux Linux unaffected 5.10.261 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.212 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.178 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.145 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.96 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.39 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.4 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/bbae351c0f32f7c200249e4aa6561b2b419dcf69 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/27ddf4486c7dbf5bdd393fa8bef6b67179796d98 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/a094ac95d3b69adfa1676eb9c8eae6835d4f1671 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/efb8763d7bbb40cff4cc55a6b62c3095a038149c 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/99206ce2244f8a3ed64298d0667c9055845a5dc7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e81f805824a8109504fce090641b17d135b48cd1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f0d88a4cd03affff6c08adf6c63964e235aede43 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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