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Google Chrome CVE-2026-106303

| EUVDEUVD-2026-93726 MEDIUM
Observable Discrepancy (CWE-203)
2026-10-06 Chrome GHSA-wfvp-3cpf-9h38
5.3
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
    Compromise renderer process via prior exploit
  2. Delivery
    Serve crafted HTML page
  3. Exploit
    Social-engineer victim interaction with Autofill AI
  4. Execution
    Observe discrepancy in Autofill AI behavior
  5. Impact
    Exfiltrate sensitive information

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V6 - Authentication Timing-safe comparisons
Exploitation Conditions

Exploitation requires the attacker to have ALREADY compromised the Chrome renderer process (e.g., via a separate sandbox-contained RCE) before this flaw is useful - this is the primary limiting factor and makes it a chained post-exploitation primitive rather than an initial-access vector. It additionally requires victim interaction obtained through social engineering (UI:R) and delivery of an attacker-crafted HTML page that engages the Autofill AI feature; the information leak stems from an observable timing/behavioral discrepancy in Autofill AI. It affects Chrome builds prior to 155.0.8059.39; patched builds are not exploitable. The compounded requirements (prior renderer compromise + user interaction + specific feature engagement) reflect the AC:H and UI:R metrics and substantially limit realistic, scalable exploitation.

Impact

This is a genuine-but-low-priority issue once context is applied. The CVSS base score of 5.3 (Medium) is driven by C:H, but the signals converge on limited real-world urgency: SSVC from CISA states Exploitation: none, Automatable: no, Technical Impact: partial, and there is no KEV listing and no public POC identified. EPSS was not provided in the input. The most important caveat is a precondition mismatch: the CVSS vector encodes PR:N (no privileges), yet the description explicitly requires 'a remote attacker who had compromised the renderer process' AND social engineering of the victim - two substantial prerequisites that the AC:H and UI:R metrics only partially capture. In practice an attacker must already have a working renderer exploit before this flaw yields value, so it is best understood as a post-exploitation information-disclosure primitive chained after a sandbox-contained compromise, not a standalone remotely triggerable bug. Treat it as a defense-in-depth fix bundled into the Chrome stable update rather than an emergency; prioritize via normal browser patch cadence.

Exploit ScenarioDerived

An attacker who has already achieved code execution inside a sandboxed Chrome renderer process serves the victim a crafted HTML page and uses social engineering to induce interaction that triggers the Autofill AI feature. The observable discrepancy (CWE-203) then leaks sensitive autofill-derived information back to the attacker-controlled renderer context. No public exploit code or active exploitation is identified at time of analysis.

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 06, 2026

Information disclosure in Google Chrome's Autofill AI component (builds prior to 155.0.8059.39) lets an attacker who has already compromised the renderer process read sensitive data by luring the victim to a crafted HTML page that engages the autofill feature. The flaw is rated CVSS 5.3 (AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N) and stems from an observable discrepancy (CWE-203) rather than a memory-safety bug, so it is a chained post-exploitation primitive, not an initial-access vector: exploitation requires a separate renderer compromise plus socially engineered user interaction, and patched builds are not exploitable. No public exploit code has been identified at time of analysis and the issue is not confirmed actively exploited (CISA KEV); CISA SSVC rates exploitation as 'none' and automatable as 'no', consistent with a genuine-but-low-priority information leak.

RemediationAI

Vendor-released patch: Chrome 155.0.8059.39 (stable channel), referenced at https://chromereleases.googleblog.com/2026/10/stable-channel-update-for-desktop_086471744.html, so the primary action is to update Chrome to 155.0.8059.39 or later on all managed endpoints and verify the installed version rather than relying on auto-update assumptions; patch data is marked 'available from vendor' and the upstream tracking issue is https://issues.chromium.org/issues/517475258. If immediate fleet-wide upgrade is not possible, treat this as a low-urgency item because exploitation demands a pre-existing renderer compromise plus user interaction, and prioritise endpoint hardening that reduces the likelihood of the prerequisite renderer foothold and of social-engineering delivery - for example blocking untrusted/unknown sites via enterprise URL filtering, hardening the browser's attack surface (site isolation, renderer sandbox enforcement, up-to-date V8 dependencies), and restricting untrusted content. Organizations may also consider disabling Chrome's autofill/AI-assisted autofill functionality through managed enterprise policy until patched, with the trade-off that this degrades user convenience and productivity and is only a partial mitigation since the information leak is a symptom of an already-compromised renderer; disabling the feature does not remediate the underlying renderer compromise that is a prerequisite for exploitation. No workaround restores full safety without the upgrade, and users should be reminded of phishing/social-engineering risk since UI:R is central to the exploit chain.

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 issue is classified as CWE-203 (Observable Discrepancy), meaning the root cause is a timing- or behavior-based side channel in Chrome's Autofill AI feature where observable differences in response allow inference of data the renderer should not be able to read. Affected builds map to the CPE cpe:2.3:a:google:chrome:*:*:*:*:*:*:*:* and EUVD lists the fixed version as 155.0.8059.39; the vulnerability resides in renderer-side autofill logic, not in the browser sandbox or IPC boundary itself, which is why the attacker is assumed to already hold renderer code execution (a position normally obtained through a separate sandbox-contained RCE) and then uses the discrepancy as a data-exfiltration primitive out of the renderer. The CVSS metrics - AV:N with AC:H, PR:N, UI:R, high confidentiality impact and no integrity/availability impact - describe exactly this: network-deliverable but hard to exploit without a pre-existing foothold and a victim who is socially engineered into visiting a crafted page. The Chromium security severity is Medium and the vector is unchanged in the independent assessment.

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Severity by source

Vendor (Chrome) PRIMARY 5.3 MEDIUM
AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
vuln.today AI 5.3 MEDIUM

AC:H and UI:R reflect the required prior renderer compromise plus social engineering; PR:N retained since no victim account privileges are needed; C:H for sensitive info disclosure, I/A:N.

3.1 AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
4.0 AV:N/AC:H/AT:N/PR:N/UI:A/VC:H/VI:N/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
High
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

Lifecycle Timeline

4
CVSS changed
Oct 06, 2026 - 20:22 NVD
5.3 (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 5.3

DescriptionCVE.org

Observable discrepancy in Autofill AI in Google Chrome prior to 155.0.8059.39 allowed a remote attacker who had compromised the renderer process and leveraged social engineering to obtain sensitive information via a crafted HTML page. (Chromium security severity: Medium)

Threat Intelligence Overview

EPSS Score
0.2%
Top 90% exploitable
Prevalence
Ubiquitous
Google Chrome is deployed across a huge fraction of desktop environments worldwide
Data Quality
7 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

26
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +26
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Vendor StatusVendor

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