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Google Chrome CVE-2026-106389

| EUVDEUVD-2026-93693 MEDIUM
Incorrect Authorization (CWE-863)
2026-10-06 Chrome GHSA-x7v5-q244-pf42
6.5
CVSS 3.1 · Vendor: Chrome
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Craft malicious Chrome extension
  2. Exploit
    Social-engineer victim into installing
  3. Execution
    Abuse USB authorization flaw
  4. Impact
    Bypass system access restrictions

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Authorization logic validation
MITRE ATT&CK

1 technique across 1 tactic: Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires the victim to be socially engineered into installing a crafted, attacker-controlled Chrome extension; it is not a remote drive-by. The flaw then lets that extension bypass USB access restrictions through incorrect authorization. Limiting factors: mandatory user interaction (UI:R) to install and run the extension, dependence on the user trusting/sideloading the extension (extensions from the Chrome Web Store undergo review, raising the bar), and the presence of relevant USB device interaction on the target. Affects Chrome versions prior to 155.0.8059.39; patched builds remove the condition. No confidentiality or availability impact is involved - the risk is integrity/access-restriction bypass only.

Impact

This is a Medium-severity Chromium flaw (CVSS 6.5, CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N) in Chrome's USB handling (CWE-863, Incorrect Authorization). The signals converge toward LOW real-world priority despite the network attack vector: EPSS is only 0.17% (6th percentile), there is no CISA KEV listing, and no public exploit code was identified. Crucially, the CVSS vector shows UI:R (user interaction required) and the description states exploitation requires social engineering plus a crafted Chrome extension - meaning the 'remote/network' vector is heavily gated by the victim having to be convinced to install an attacker-controlled extension, not by a drive-by remote exploit. Impact is integrity-only (I:H, C:N, A:N), reflecting a system-access-restriction bypass via USB rather than data theft or crash. The low EPSS is consistent with the absence of KEV/POC and the high interaction barrier. No conflicting signals of note; the main caveat is that this is a vendor (Chrome) self-reported issue with limited third-party corroboration of exploitability.

Exploit ScenarioDerived

An attacker publishes or distributes a malicious Chrome extension and uses social engineering (phishing, fake utility, deceptive listing) to persuade a victim to install it. Once installed and granted interaction, the extension abuses the incorrect authorization in Chrome's USB implementation to bypass system access restrictions and interact with USB devices beyond its intended permissions. No public exploit code was identified at time of analysis, so this remains a plausible but unproven chain.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 08, 2026

Incorrect authorization in Google Chrome's USB handling (CWE-863) allows a malicious, attacker-controlled Chrome extension to bypass system access restrictions on USB devices in Chrome versions prior to 155.0.8059.39. Exploitation is not a remote drive-by: it requires the victim to be socially engineered into installing and running the crafted extension, which is reflected in the assessed vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N (6.5, Medium) - unauthenticated over the network, but gated by mandatory user interaction, with integrity/access-restriction impact only and no confidentiality or availability impact. There is no confirmed active exploitation (not in CISA KEV), no public exploit code identified at time of analysis, and EPSS is low at 0.17% (6th percentile). A vendor patch is available in Chrome 155.0.8059.39.

RemediationAI

Vendor-released patch: Google Chrome 155.0.8059.39. Upgrade every affected Chrome installation to 155.0.8059.39 or later - users can force the update via chrome://settings/help (or the equivalent managed auto-update channel), and enterprises should push the fixed build through their software distribution tooling and verify the reported version, since the underlying Chromium change is documented in https://issues.chromium.org/issues/503625361 and the release announcement at https://chromereleases.googleblog.com/2026/10/stable-channel-update-for-desktop_086471744.html. Because exploitation requires the user to install a crafted extension, the most effective compensating control before patching is extension control: enforce an ExtensionSettings/ExtensionInstallAllowlist policy so only vetted extensions can be installed, set ExtensionInstallBlocklist to "*" for unmanaged sources, and disable sideloading/developer mode (on Windows, block external extension installation via the registry ExtensionInstallBlocklist and ExtensionInstallSources policies) - the trade-off is that legitimate extension workflows and internal tooling relying on sideloaded CRX files will break and require explicit allowlisting. Additionally, organizations that do not need browser USB access can set the DefaultWebUsbGuardSetting policy to 2 (block WebUSB entirely) and restrict the chrome.usb extension API via enterprise policy, which removes the attack surface but will disable legitimate WebUSB/serial hardware (badge readers, kiosk peripherals, test devices) for users. Restricting which users can attach USB devices at the OS level (endpoint device control / USB blocklisting) provides defense in depth with the operational cost of blocking all USB peripherals, not just browser-initiated access. Monitor Chrome auto-update telemetry to confirm fleet-wide remediation to 155.0.8059.39, as no vendor-released patch exists for older builds other than upgrading to this version.

Affected VersionsENISA

Chrome 155.0.8059.39 <155.0.8059.39

Affected Packages

euvd chrome fix: 155.0.8059.39

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The flaw is an incorrect authorization defect (CWE-863) in the USB subsystem of Chromium/Google Chrome, the layer that mediates extension and web content access to locally attached USB devices (the chrome.usb extension API and the underlying device permission/authorization checks). Rather than enforcing the expected authorization decision before granting a caller access to a USB device, the affected code path permits an installed, attacker-crafted extension to sidestep the platform's system-level USB access restrictions. Chromium's own security severity rating for this issue is Medium, consistent with the CVSS 6.5 assessment: the integrity of the access-control decision is broken (I:H), but there is no exposure of confidential data and no denial-of-service component (C:N/A:N). The attack is network-delivered (AV:N) and low-complexity (AC:L) with no required privileges (PR:N), but it is contingent on user interaction (UI:R) to install and run the extension, and it depends on the target host having relevant USB device interaction. Affected software is identified by the CPE cpe:2.3:a:google:chrome:*:*:*:*:*:*:*:*, i.e. Google Chrome builds earlier than 155.0.8059.39; Chromium-derived browsers that consume the same upstream USB authorization code may inherit the condition until rebased. The referenced Chromium issue (issues.chromium.org/issues/503625361) tracks the upstream fix.

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Severity by source

Vendor (Chrome) PRIMARY 6.5 MEDIUM
AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
vuln.today AI 6.5 MEDIUM

Delivered remotely via a crafted extension (AV:N) but requires the user to install and run it (UI:R, PR:N); impact is an access-restriction bypass, so I:H with C:N/A:N.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Red Hat 6.5 MEDIUM

Primary rating from Vendor (Chrome).

CVSS VectorVendor: Chrome

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

Lifecycle Timeline

4
CVSS changed
Oct 08, 2026 - 17:23 NVD
6.5 (MEDIUM)
Patch available
Oct 06, 2026 - 20:04 EUVD
CVE Published
Oct 06, 2026 - 18:41 cve.org
UNKNOWN (no severity yet)
CVE Published
Oct 06, 2026 - 18:41 cve.org
MEDIUM 6.5

DescriptionCVE.org

Incorrect authorization in USB in Google Chrome prior to 155.0.8059.39 allowed a remote attacker leveraging social engineering to bypass system access restrictions via a crafted Chrome extension. (Chromium security severity: Medium)

Threat Intelligence Overview

EPSS Score
0.2%
Top 94% exploitable
Prevalence
Ubiquitous
Google Chrome is deployed across a huge fraction of desktop environments
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

32
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +32
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

Vendor StatusVendor

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