Linux: Integer Overflow or Wraparound
CVE-2026-64422 is a high-severity integer overflow or wraparound vulnerability in Linux, with a CVSS 3.1 base score of 7.1 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions f0d88a4cd03affff6c08adf6c63964e235aede43, 27ddf4486c7dbf5bdd393fa8bef6b67179796d98, 782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.14% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to f0d88a4cd03affff6c08adf6c63964e235aede43 or 27ddf4486c7dbf5bdd393fa8bef6b67179796d98 or 782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae or e81f805824a8109504fce090641b17d135b48cd1, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.261 or 5.15.212 or 6.1.178 or 6.6.145, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf up to, but not including, f0d88a4cd03affff6c08adf6c63964e235aede43; 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf up to, but not including, 27ddf4486c7dbf5bdd393fa8bef6b67179796d98; 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf up to, but not including, 782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae; 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf up to, but not including, e81f805824a8109504fce090641b17d135b48cd1; 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf up to, but not including, 99206ce2244f8a3ed64298d0667c9055845a5dc7; 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf up to, but not including, bbae351c0f32f7c200249e4aa6561b2b419dcf69; 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf up to, but not including, a094ac95d3b69adfa1676eb9c8eae6835d4f1671; 91cc17c0e5e5ada156a8d5787a2509d263ea6bbf up to, but not including, efb8763d7bbb40cff4cc55a6b62c3095a038149c; and 1 more ranges | f0d88a4cd03affff6c08adf6c63964e235aede43, 27ddf4486c7dbf5bdd393fa8bef6b67179796d98, 782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae, e81f805824a8109504fce090641b17d135b48cd1, 99206ce2244f8a3ed64298d0667c9055845a5dc7, bbae351c0f32f7c200249e4aa6561b2b419dcf69 |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Linux | Linux Kernel | 2.6.24.1 up to, but not including, 5.10.261; 5.11 up to, but not including, 5.15.212; 5.16 up to, but not including, 6.1.178; 6.2 up to, but not including, 6.6.145; 6.7 up to, but not including, 6.12.96; 6.13 up to, but not including, 6.18.39; 6.19 up to, but not including, 7.1.4; 2.6.24 | 5.10.261, 5.15.212, 6.1.178, 6.6.145, 6.12.96, 6.18.39 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H. Scored by CNA.
Official 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.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Integer Overflow or Wraparound
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
How developers prevent this class of flaw
- Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. If possible, choose a language or compiler that performs automatic bounds checking.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Use libraries or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).
More Integer Overflow or Wraparound vulnerabilities (CWE-190)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/27ddf4486c7dbf5bdd393fa8bef6b67179796d98
- git.kernel.org/stable/c/782708ca1ea1f68b8cbb5ea3a7f5f18d0000efae
- git.kernel.org/stable/c/99206ce2244f8a3ed64298d0667c9055845a5dc7
- git.kernel.org/stable/c/a094ac95d3b69adfa1676eb9c8eae6835d4f1671
- git.kernel.org/stable/c/bbae351c0f32f7c200249e4aa6561b2b419dcf69
- git.kernel.org/stable/c/e81f805824a8109504fce090641b17d135b48cd1
- git.kernel.org/stable/c/efb8763d7bbb40cff4cc55a6b62c3095a038149c
- git.kernel.org/stable/c/f0d88a4cd03affff6c08adf6c63964e235aede43
Other references
Recent Integer Overflow or Wraparound vulnerabilities
- 8.8 High severity
- 7.8 High severity
- 8.8 High severity
- 7.0 High severity
- 9.8 Critical severity
- 9.3 Critical severity
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