Linux: Out-of-bounds Write
CVE-2026-23359 is a high-severity out-of-bounds write vulnerability in Linux, with a CVSS 3.1 base score of 7.8 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 88df604f0d16a692867582350ce3f2fcd22243f1, 5000e40acc8d0c36ab709662e32120986ac22e7e, 8a95fb9df1105b1618872c2846a6c01e3ba20b45 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 88df604f0d16a692867582350ce3f2fcd22243f1 or 5000e40acc8d0c36ab709662e32120986ac22e7e or 8a95fb9df1105b1618872c2846a6c01e3ba20b45 or d2c31d8e03d05edc16656e5ffe187f0d1da763d7, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.203 or 6.1.167 or 6.6.130 or 6.12.77, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | aeea1b86f9363f3feabb496534d886f082a89f21 up to, but not including, 88df604f0d16a692867582350ce3f2fcd22243f1; aeea1b86f9363f3feabb496534d886f082a89f21 up to, but not including, 5000e40acc8d0c36ab709662e32120986ac22e7e; aeea1b86f9363f3feabb496534d886f082a89f21 up to, but not including, 8a95fb9df1105b1618872c2846a6c01e3ba20b45; aeea1b86f9363f3feabb496534d886f082a89f21 up to, but not including, d2c31d8e03d05edc16656e5ffe187f0d1da763d7; aeea1b86f9363f3feabb496534d886f082a89f21 up to, but not including, 75d474702b2ba8b6bcb26eb3004dbc5e95ffd5d2; aeea1b86f9363f3feabb496534d886f082a89f21 up to, but not including, ca831567908fd3f73cf97d8a6c09a5054697a182; aeea1b86f9363f3feabb496534d886f082a89f21 up to, but not including, b7bf516c3ecd9a2aae2dc2635178ab87b734fef1; 5.15 | 88df604f0d16a692867582350ce3f2fcd22243f1, 5000e40acc8d0c36ab709662e32120986ac22e7e, 8a95fb9df1105b1618872c2846a6c01e3ba20b45, d2c31d8e03d05edc16656e5ffe187f0d1da763d7, 75d474702b2ba8b6bcb26eb3004dbc5e95ffd5d2, ca831567908fd3f73cf97d8a6c09a5054697a182 |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.6 and later; V3.1.5 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; V3.1.5 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; V3.1.5 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; V3.1.5 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 TM MFP - GNU/Linux subsystem | all versions | Not stated |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | V3.1.6 and later; V3.1.5 and later; V3.1.7 and later | Not stated |
| Linux | Linux Kernel | 5.15.1 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.167; 6.2 up to, but not including, 6.6.130; 6.7 up to, but not including, 6.12.77; 6.13 up to, but not including, 6.18.17; 6.19 up to, but not including, 6.19.7; 5.15; 7.0 | 5.15.203, 6.1.167, 6.6.130, 6.12.77, 6.18.17, 6.19.7 |
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
- HighData or code can be modified at will.
- 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:H/A:H. Scored by NVD.
Official description
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix stack-out-of-bounds write in devmap get_upper_ifindexes() iterates over all upper devices and writes their indices into an array without checking bounds. Also the callers assume that the max number of upper devices is MAX_NEST_DEV and allocate excluded_devices[1+MAX_NEST_DEV] on the stack, but that assumption is not correct and the number of upper devices could be larger than MAX_NEST_DEV (e.g., many macvlans), causing a stack-out-of-bounds write. Add a max parameter to get_upper_ifindexes() to avoid the issue. When there are too many upper devices, return -EOVERFLOW and abort the redirect. To reproduce, create more than MAX_NEST_DEV(8) macvlans on a device with an XDP program attached using BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS. Then send a packet to the device to trigger the XDP redirect path.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
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/5000e40acc8d0c36ab709662e32120986ac22e7e
- git.kernel.org/stable/c/75d474702b2ba8b6bcb26eb3004dbc5e95ffd5d2
- git.kernel.org/stable/c/88df604f0d16a692867582350ce3f2fcd22243f1
- git.kernel.org/stable/c/8a95fb9df1105b1618872c2846a6c01e3ba20b45
- git.kernel.org/stable/c/b7bf516c3ecd9a2aae2dc2635178ab87b734fef1
- git.kernel.org/stable/c/ca831567908fd3f73cf97d8a6c09a5054697a182
- git.kernel.org/stable/c/d2c31d8e03d05edc16656e5ffe187f0d1da763d7
Other references
Recent Out-of-bounds Write vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
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