VulnerabilityPublished 24 Apr 2026Updated 19 Oct 2026

CVE-2026-31613: Linux kernel · Out-of-bounds Read

Affects Linux kernelSource CVE Database V5

Not known to be exploited · CVSS 8.1 High · fixed in e0dd90d14cbbf318157ea8e3fb62ee68a28655ed : patch Linux kernel soon.

Data as of 26 Oct 2026, 13:47 UTC

CVSS 3.1 base score

8.1High

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

EPSS

0.3% chance of exploitation in 30 days – higher than 32% 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 cannot 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 e0dd90d14cbbf318157ea8e3fb62ee68a28655ed, d65a64755a3df68a2fd19d2a81395e9f723aca23, a66ef2e7ed837325c5600f8617d5ee0a0a149fdd +5

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: High
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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
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: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
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 to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=6.0.16 <6.1	Fixed in e0dd90d14cbbf318157ea8e3fb62ee68a28655ed d65a64755a3df68a2fd19d2a81395e9f723aca23 a66ef2e7ed837325c5600f8617d5ee0a0a149fdd 781902e069f4ecb6c3b83502f181972c1446110a 043834e72337ee7b4e9685859888623ba1504ac7 20ac98f0eb6047edb73c9a27af782bdde08b3757 6.1 3df690bba28edec865cf7190be10708ad0ddd67e
LinuxLinux	Affected =6.1	Fixed in–

AI-suggested

This vulnerability has been fixed in Linux kernel version 6.1 and later. Users and administrators should upgrade affected Linux kernel versions (>=6.0.16 <6.1 and =6.1) to the fixed versions to mitigate this issue. No additional mitigations are required once the kernel is updated.

Description

CVE-2026-31613 is a high-severity vulnerability in the Linux kernel SMB client that allows out-of-bounds (OOB) reads when parsing symlink error responses. The flaw arises from improper length validation in smb2_check_message() and incorrect bounds checking in smb2_parse_symlink_response(), which can cause heap memory beyond allocated buffers to be read and returned to userspace. This issue affects Linux kernel versions 6.0.16 up to but not including 6.1, and version 6.1 exactly. The vulnerability has been fixed in Linux kernel 6.1 and later commits.

Impact

An attacker controlling an SMB server can exploit this vulnerability to cause out-of-bounds heap reads in the Linux kernel SMB client when processing symlink error responses. This can lead to disclosure of kernel memory contents to userspace via readlink(2). The vulnerability does not indicate direct code execution or integrity impact but has high confidentiality impact and causes a denial of service (crash) due to the out-of-bounds read. There are no known exploits in the wild as of the published date.

CWE-125Out-of-bounds Read (opens in a new tab)
Base weaknessCWE Top 25 (2025): #8
The product reads data past the end, or before the beginning, of the intended buffer.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Architecture and Design · Language Selection
Use a language that provides appropriate memory abstractions.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Overread Buffers (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

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

WeaknessesCWE-125

Technical details

References

Community reviews

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