VulnerabilityPublished 18 Oct 2026Updated 24 Oct 2026

CVE-2026-98454: Linux kernel · smb: client: fix create context out-of-bounds reads

Affects Linux kernelSource CVE Database V5

Not known to be exploited · CVSS 8.1 High · fixed in e4c49012708c917eafd9c27054b02d0f8b30fe64 : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:00 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 27% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in e4c49012708c917eafd9c27054b02d0f8b30fe64, cecc5399987e73a528ce2b662eeb54af69163cbd, 67f4c1c6a1b51e203d986779299824d1c2c590a6 +2

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 18 Oct 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 ≥ b8c32dbb0deb287a5fcb78251e4eae6c7275760d, < e4c49012708c917eafd9c27054b02d0f8b30fe64	Fixed in e4c49012708c917eafd9c27054b02d0f8b30fe64
LinuxLinux	Affected ≥ b8c32dbb0deb287a5fcb78251e4eae6c7275760d, < cecc5399987e73a528ce2b662eeb54af69163cbd	Fixed in cecc5399987e73a528ce2b662eeb54af69163cbd
LinuxLinux	Affected ≥ b8c32dbb0deb287a5fcb78251e4eae6c7275760d, < 67f4c1c6a1b51e203d986779299824d1c2c590a6	Fixed in 67f4c1c6a1b51e203d986779299824d1c2c590a6
LinuxLinux	Affected ≥ b8c32dbb0deb287a5fcb78251e4eae6c7275760d, < 28bc9a871799363afa3139e961a8e3684feb8704	Fixed in 28bc9a871799363afa3139e961a8e3684feb8704
LinuxLinux	Affected ≥ b8c32dbb0deb287a5fcb78251e4eae6c7275760d, < 05a7fd80024ff32b9b40ab1478bb172eeab1c386	Fixed in 05a7fd80024ff32b9b40ab1478bb172eeab1c386
LinuxLinux	Affected =3.7	Fixed in–

AI-suggested

A fix is available and has been committed in multiple Linux kernel versions as indicated by the fixed commit hashes. Users and administrators should update to a Linux kernel version that includes these fixes. Since this is not a cloud service, manual patching is required. No additional mitigations are specified by the vendor advisory.

Description

CVE-2026-98454 is a high-severity vulnerability in the Linux kernel's SMB client implementation. It involves out-of-bounds reads in the create context parsing logic of SMB2/SMB3 protocols. The flaw arises because the code does not properly limit each create context record to its declared size before processing, allowing malformed input to expose unintended memory bytes. The vulnerability affects the handling of QFid and lease contexts, potentially leading to information disclosure and denial of service.

Impact

This vulnerability can lead to out-of-bounds memory reads when processing SMB create contexts, potentially exposing sensitive kernel memory contents to an attacker. The CVSS score of 8.1 indicates high severity with network attack vector, no privileges required, user interaction needed, and high confidentiality and availability impact. There is no indication of known exploits in the wild. The flaw could be leveraged to cause denial of service or information disclosure.

Summary

The vulnerability in the Linux kernel SMB client lies in smb2_parse_contexts(), which validates the overall create-context area but fails to restrict each individual record to its Next field length before dispatching handlers. This allows a malformed chain of contexts to cause out-of-bounds reads beyond the current context. Specifically, the QFid handler incorrectly casts the entire response structure but only reads the DiskFileId field, and the SMB2/SMB3 lease parsers assume fixed offsets rather than using the DataOffset field, which can lead to reading unrelated data. The fix involves bounding each context by its Next value, rejecting malformed chains and invalid offsets, and validating DataLength against expected lease context sizes. The patch ensures safer parsing and prevents exposure of memory beyond intended bounds.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 09:40 UTC

Technical details

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