VulnerabilityPublished 24 Apr 2026Updated 19 Oct 2026

CVE-2026-31600: Linux kernel · arm64: mm: Handle invalid large leaf mappings correctly

Affects Linux kernelSource CVE Database V5

Not known to be exploited · CVSS 7.5 High · fixed in cbea627ea634f41c79d18f0c6d20db66fa93514c : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:18 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS

0.2% chance of exploitation in 30 days – higher than 21% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers can reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-10-16.

Patch

Available – fixed in cbea627ea634f41c79d18f0c6d20db66fa93514c, 8140b21d19015227a28c255404462f2d3e6edc9a, 747b6482e4e227fd351197dde6f64a97107a9e52 +1

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 24 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade Linux kernel to cbea627ea634f41c79d18f0c6d20db66fa93514c, 8140b21d19015227a28c255404462f2d3e6edc9a, 747b6482e4e227fd351197dde6f64a97107a9e52 or 15bfba1ad77fad8e45a37aae54b3c813b33fe27c.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ a166563e7ec375b38a0fd3a58f7b77e50a6bc6a8, < cbea627ea634f41c79d18f0c6d20db66fa93514c	Fixed in cbea627ea634f41c79d18f0c6d20db66fa93514c
LinuxLinux	Affected ≥ a166563e7ec375b38a0fd3a58f7b77e50a6bc6a8, < 8140b21d19015227a28c255404462f2d3e6edc9a	Fixed in 8140b21d19015227a28c255404462f2d3e6edc9a
LinuxLinux	Affected ≥ a166563e7ec375b38a0fd3a58f7b77e50a6bc6a8, < 747b6482e4e227fd351197dde6f64a97107a9e52	Fixed in 747b6482e4e227fd351197dde6f64a97107a9e52
LinuxLinux	Affected ≥ a166563e7ec375b38a0fd3a58f7b77e50a6bc6a8, < 15bfba1ad77fad8e45a37aae54b3c813b33fe27c	Fixed in 15bfba1ad77fad8e45a37aae54b3c813b33fe27c
LinuxLinux	Affected =6.18	Fixed in–

AI-suggested

A fix for this vulnerability is available in the Linux kernel commits identified by hashes cbea627ea634f41c79d18f0c6d20db66fa93514c, 8140b21d19015227a28c255404462f2d3e6edc9a, 747b6482e4e227fd351197dde6f64a97107a9e52, and 15bfba1ad77fad8e45a37aae54b3c813b33fe27c. Users and administrators should update to a patched kernel version incorporating these fixes to remediate the issue. No other mitigations or workarounds are indicated.

Description

CVE-2026-31600 is a vulnerability in the Linux kernel's arm64 memory management subsystem. It involves improper handling of invalid large leaf page table entries (PTEs), which can cause kernel panics during certain memory operations. This flaw was triggered by marking large leaf mappings as invalid, a scenario not properly supported before a recent kernel commit. The issue can lead to a denial of service via kernel crash. The vulnerability affects Linux kernel version 6.18 and has been fixed in subsequent commits.

Impact

The vulnerability can cause a kernel panic resulting in a denial of service (DoS) condition. There is no indication of confidentiality or integrity impact. The CVSS score is 7.5 (high severity) with no privileges required and no user interaction needed. The impact is limited to availability due to kernel crashes triggered by invalid large leaf mappings in the arm64 memory management subsystem.

Summary

This vulnerability in the Linux kernel arm64 memory management code arises from incorrect handling of invalid large leaf mappings in page tables. Previously, large leaf mappings were not marked invalid in the same way as smaller mappings, leading to parts of the kernel code being unprepared for such invalid entries. This caused kernel panics, as demonstrated by a crash during booting a realm guest on a BBML2_NOABORT system. The issue was resolved by correcting the handling of these invalid large leaf mappings. The vulnerability is tracked as CVE-2026-31600 and affects Linux kernel version 6.18. Multiple commits have fixed the issue.

CWE-476NULL Pointer Dereference (opens in a new tab)
Base weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #13OWASP Top 10 A10:2025: Mishandling of Exceptional Conditions (opens in a new tab)
The product dereferences a pointer that it expects to be valid but is NULL.
Implementation
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.
Requirements
Select a programming language that is not susceptible to these issues.
Implementation
Check the results of all functions that return a value and verify that the value is non-null before acting upon it.
OWASP Cheat Sheets
Logging (opens in a new tab)
Error Handling (opens in a new tab)
OWASP ASVS 4.0.3
V11.1.7 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 13:45 UTC

WeaknessesCWE-476

Technical details

References

Community reviews

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