Linux: NULL Pointer Dereference
CVE-2026-43099 is a high-severity NULL pointer dereference vulnerability in Linux, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 0f21bc261e60f0c696c58841c4873ff77ed83673, dc5db4db19766a61ad65d81d1f55b1c1e51ba78d, 47a8bf52156ac7e7a581eca31c1f964ba4258d4d 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 0.5% 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 0f21bc261e60f0c696c58841c4873ff77ed83673 or dc5db4db19766a61ad65d81d1f55b1c1e51ba78d or 47a8bf52156ac7e7a581eca31c1f964ba4258d4d or 6be325206850a0891896d38bcf83a09d8b54ec48, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.136 or 6.12.83 or 6.18.24 or 6.19.14, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | d329ea5bd8845f0b196bf41b18b6173340d6e0e4 up to, but not including, 0f21bc261e60f0c696c58841c4873ff77ed83673; d329ea5bd8845f0b196bf41b18b6173340d6e0e4 up to, but not including, dc5db4db19766a61ad65d81d1f55b1c1e51ba78d; d329ea5bd8845f0b196bf41b18b6173340d6e0e4 up to, but not including, 47a8bf52156ac7e7a581eca31c1f964ba4258d4d; d329ea5bd8845f0b196bf41b18b6173340d6e0e4 up to, but not including, 6be325206850a0891896d38bcf83a09d8b54ec48; d329ea5bd8845f0b196bf41b18b6173340d6e0e4 up to, but not including, f91b3ed9e7fa82a70511b5f6901c88379acf2964; d329ea5bd8845f0b196bf41b18b6173340d6e0e4 up to, but not including, 5b9911582d441f72fe6ccb15ffe3303bbc07f6f5; d329ea5bd8845f0b196bf41b18b6173340d6e0e4 up to, but not including, fde29fd9349327acc50d19a0b5f3d5a6c964dfd8; 5.13 | 0f21bc261e60f0c696c58841c4873ff77ed83673, dc5db4db19766a61ad65d81d1f55b1c1e51ba78d, 47a8bf52156ac7e7a581eca31c1f964ba4258d4d, 6be325206850a0891896d38bcf83a09d8b54ec48, f91b3ed9e7fa82a70511b5f6901c88379acf2964, 5b9911582d441f72fe6ccb15ffe3303bbc07f6f5 |
| Siemens | SIMATIC S7-1500 TM MFP - GNU/Linux subsystem | all versions | Not stated |
| Linux | Linux Kernel | 5.13 up to, but not including, 6.6.136; 6.7 up to, but not including, 6.12.83; 6.13 up to, but not including, 6.18.24; 6.19 up to, but not including, 6.19.14; 7.0 | 6.6.136, 6.12.83, 6.18.24, 6.19.14 |
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
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA.
Official description
In the Linux kernel, the following vulnerability has been resolved: ipv4: icmp: fix null-ptr-deref in icmp_build_probe() ipv6_stub->ipv6_dev_find() may return ERR_PTR(-EAFNOSUPPORT) when the IPv6 stack is not active (CONFIG_IPV6=m and not loaded), and passing this error pointer to dev_hold() will cause a kernel crash with null-ptr-deref. Instead, silently discard the request. RFC 8335 does not appear to define a specific response for the case where an IPv6 interface identifier is syntactically valid but the implementation cannot perform the lookup at runtime, and silently dropping the request may safer than misreporting "No Such Interface".
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: NULL Pointer Dereference
The product dereferences a pointer that it expects to be valid but is NULL.
How developers prevent this class of flaw
- For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
- Select a programming language that is not susceptible to these issues.
- Check the results of all functions that return a value and verify that the value is non-null before acting upon it.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/47a8bf52156ac7e7a581eca31c1f964ba4258d4d
- git.kernel.org/stable/c/5b9911582d441f72fe6ccb15ffe3303bbc07f6f5
- git.kernel.org/stable/c/6be325206850a0891896d38bcf83a09d8b54ec48
- git.kernel.org/stable/c/f91b3ed9e7fa82a70511b5f6901c88379acf2964
- git.kernel.org/stable/c/fde29fd9349327acc50d19a0b5f3d5a6c964dfd8
Other references
Recent NULL Pointer Dereference vulnerabilities
- 7.8 High severity
- 7.5 High severity
- 7.8 High severity
- 7.5 High severity
- 9.1 Critical severity
- 8.8 High severity
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