Linux: NULL Pointer Dereference
CVE-2026-52998 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 f4de0777e4554a7de19c920accde6319dd530782, c996a90f3071cf43683e5423da31aadbe002b8b4, edc806f9122961f0d3819f7c69c14cccde31f277 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 0.58% 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 f4de0777e4554a7de19c920accde6319dd530782 or c996a90f3071cf43683e5423da31aadbe002b8b4 or edc806f9122961f0d3819f7c69c14cccde31f277 or 5d05de2f0928d81309a815ecc76d1a3ad72cbc16, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.10.258 or 5.15.209 or 6.1.175 or 6.6.141, 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 | 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 up to, but not including, f4de0777e4554a7de19c920accde6319dd530782; 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 up to, but not including, c996a90f3071cf43683e5423da31aadbe002b8b4; 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 up to, but not including, edc806f9122961f0d3819f7c69c14cccde31f277; 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 up to, but not including, 5d05de2f0928d81309a815ecc76d1a3ad72cbc16; 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 up to, but not including, 95be653a76793856ff8b2d8bd82c2943c23f5ca8; 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 up to, but not including, 79b90a96688e521771fa6ed3dc7864b76b8df293; 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 up to, but not including, 83fc5dd63455a779ea2dd0f7ffee3c920919d80b; 11eeef41d5f63c7d2f7fdfcc733eb7fb137cc384 up to, but not including, 711987ba281fd806322a7cd244e98e2a81903114; and 1 more ranges | f4de0777e4554a7de19c920accde6319dd530782, c996a90f3071cf43683e5423da31aadbe002b8b4, edc806f9122961f0d3819f7c69c14cccde31f277, 5d05de2f0928d81309a815ecc76d1a3ad72cbc16, 95be653a76793856ff8b2d8bd82c2943c23f5ca8, 79b90a96688e521771fa6ed3dc7864b76b8df293 |
| 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 | 2.6.31 up to, but not including, 5.10.258; 5.11 up to, but not including, 5.15.209; 5.16 up to, but not including, 6.1.175; 6.2 up to, but not including, 6.6.141; 6.7 up to, but not including, 6.12.91; 6.13 up to, but not including, 6.18.33; 6.19 up to, but not including, 7.0.10 | 5.10.258, 5.15.209, 6.1.175, 6.6.141, 6.12.91, 6.18.33 |
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: netfilter: nfnetlink_osf: fix potential NULL dereference in ttl check The nf_osf_ttl() function accessed skb->dev to perform a local interface address lookup without verifying that the device pointer was valid. Additionally, the implementation utilized an in_dev_for_each_ifa_rcu loop to match the packet source address against local interface addresses. It assumed that packets from the same subnet should not see a decrement on the initial TTL. A packet might appear it is from the same subnet but it actually isn't especially in modern environments with containers and virtual switching. Remove the device dereference and interface loop. Replace the logic with a switch statement that evaluates the TTL according to the ttl_check.
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.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/5d05de2f0928d81309a815ecc76d1a3ad72cbc16
- git.kernel.org/stable/c/711987ba281fd806322a7cd244e98e2a81903114
- git.kernel.org/stable/c/79b90a96688e521771fa6ed3dc7864b76b8df293
- git.kernel.org/stable/c/83fc5dd63455a779ea2dd0f7ffee3c920919d80b
- git.kernel.org/stable/c/95be653a76793856ff8b2d8bd82c2943c23f5ca8
- git.kernel.org/stable/c/c996a90f3071cf43683e5423da31aadbe002b8b4
- git.kernel.org/stable/c/edc806f9122961f0d3819f7c69c14cccde31f277
- git.kernel.org/stable/c/f4de0777e4554a7de19c920accde6319dd530782
Other references
Recent NULL Pointer Dereference vulnerabilities
- 7.8 High severity
- 7.5 High severity
- 9.8 Critical severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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