CVE-2026-64422net: ipv4: bound TCP reordering sysctl writes and MTU probe sizes
- 7.1HighCVSS base score
- 0.14%Exploitation in 30 daysEPSS · top 97% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By Linux
- 6 days later
· 6 days later
Published
- 4 months later
· 4 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| LinuxCNA (assigner) | 3.1 | High7.1 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H |
| NVDNVD · Modified | 3.1 | High7.1 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.14% · top 97% of all CVEs (15 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.1.
Affected products
- affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf – < f0d88a4cd03affff6c08adf6c63964e235aede43
- affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf – < 27ddf4486c7dbf5bdd393fa8bef6b67179796d98
- affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf – < 782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae
- affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf – < e81f805824a8109504fce090641b17d135b48cd1
- affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf – < 99206ce2244f8a3ed64298d0667c9055845a5dc7
- affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf – < bbae351c0f32f7c200249e4aa6561b2b419dcf69
- affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf – < a094ac95d3b69adfa1676eb9c8eae6835d4f1671
- affected 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf – < efb8763d7bbb40cff4cc55a6b62c3095a038149c
- affected 2.6.24
- unaffected < 2.6.24
- unaffected 5.10.261 – ≤ 5.10.*
- unaffected 5.15.212 – ≤ 5.15.*
- unaffected 6.1.178 – ≤ 6.1.*
- unaffected 6.6.145 – ≤ 6.6.*
- unaffected 6.12.96 – ≤ 6.12.*
- unaffected 6.18.39 – ≤ 6.18.*
- unaffected 7.1.4 – ≤ 7.1.*
- unaffected 7.2 – ≤ *
References
References10
- https://git.kernel.org/stable/c/f0d88a4cd03affff6c08adf6c63964e235aede43 (opens in a new tab)
- https://git.kernel.org/stable/c/27ddf4486c7dbf5bdd393fa8bef6b67179796d98 (opens in a new tab)
- https://git.kernel.org/stable/c/782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae (opens in a new tab)
- https://git.kernel.org/stable/c/e81f805824a8109504fce090641b17d135b48cd1 (opens in a new tab)
- https://git.kernel.org/stable/c/99206ce2244f8a3ed64298d0667c9055845a5dc7 (opens in a new tab)
- https://git.kernel.org/stable/c/bbae351c0f32f7c200249e4aa6561b2b419dcf69 (opens in a new tab)
- https://git.kernel.org/stable/c/a094ac95d3b69adfa1676eb9c8eae6835d4f1671 (opens in a new tab)
- https://git.kernel.org/stable/c/efb8763d7bbb40cff4cc55a6b62c3095a038149c (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-48966 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-64422)Record last updated .