CVE-2026-86540

Arbitrary code execution via unvalidated LSP binary

Published Sep 7, 2026 · Updated Sep 8, 2026

OS command injection in Knowns before 0.30.0 allows attackers to execute arbitrary binaries by opening a crafted project repository. ProjectSettings.Validate ignores settings.lsp.languages..binary, and Detector.resolve passes the resulting path to a version check before Server.Start spawns it again. Opening an attacker-controlled repository is required, after which both executions run under the affected user's account.

CVSS severity8.5
High
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OS command injection in Knowns before 0.30.0 allows attackers to execute arbitrary binaries by opening a crafted project repository. ProjectSettings.Validate ignores settings.lsp.languages..binary, and Detector.resolve passes the resulting path to a version check before Server.Start spawns it again. Opening an attacker-controlled repository is required, after which both executions run under the affected user's account.

The record

CVE
CVE-2026-86540
Published
Sep 7, 2026
Updated
Sep 8, 2026
Vendor
Knowns
Product
Knowns
Classifications
CWE-78, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 7, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <0.30.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Knowns · Knownsversion=0 <0.30.0

Published CVSS scores

8.5National Vulnerability DatabaseCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
7.8KnownsCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1204.002User Execution: Malicious File

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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