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Google Chrome EUVDEUVD-2026-82484

| CVE-2026-93380 LOW
Time-of-check Time-of-use (TOCTOU) Race Condition (CWE-367)
2026-09-17 chrome-cve-admin@google.com GHSA-g879-8xg4-pm93
3.1
CVSS 3.1 · Vendor: google
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Attack ChainAIDerived

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

  1. Access
    Compromise renderer via separate bug
  2. Delivery
    Lure victim to crafted HTML page
  3. Exploit
    Win filesystem TOCTOU race
  4. Execution
    Bypass system access restrictions
  5. Impact
    Access files outside sandbox limits

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture TOCTOU prevention
Exploitation Conditions

Exploitation requires the attacker to have ALREADY compromised the Chrome renderer process (a prior, separate vulnerability), then leverage social engineering to make the victim open a crafted HTML page, and finally win a filesystem race condition (TOCTOU) to bypass system access restrictions. Limiting factors: it is not a standalone entry point (needs pre-existing renderer compromise), it requires user interaction (UI:R), and the race condition gives high attack complexity (AC:H) meaning exploitation is timing-dependent and unreliable. Affects Chrome versions prior to 153.0.8010.52; patched builds are not exploitable.

Impact

This is a low-real-risk, low-CVSS issue despite being a network-vector browser flaw. The vendor CVSS 3.1 score of 3.1 (AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N) is honest: exploitation carries high attack complexity (AC:H, inherent to winning a TOCTOU race), requires user interaction (UI:R via social engineering to open a crafted page), and - critically - the description states the attacker must ALREADY have compromised the renderer process. That precondition, not captured in the CVSS PR metric (kept at PR:N because no Chrome-level authentication is bypassed), means this is only useful as a secondary link in a chain, never a standalone entry point. Impact is limited (C:N/I:L/A:N - a limited bypass of system access restrictions, i.e. partial filesystem-sandbox boundary weakening). No EPSS score, no CISA KEV listing, and no public POC were provided; per the precision rules this is 'no public exploit identified at time of analysis.' Chromium itself rated it Medium. Conflicting signal to flag: the input Tags label this 'Authentication Bypass,' but CWE-367 and the description make clear it is a race-condition/TOCTOU sandbox-restriction bypass, not an authentication bypass - verify tag before triage. Net: real code fix worth patching via normal Chrome auto-update cadence, but not an urgent standalone priority.

Exploit ScenarioDerived

An attacker who has already exploited a separate renderer-process bug lures a victim into visiting a crafted HTML page and wins a filesystem race condition (TOCTOU) to bypass system access restrictions and reach files outside the sandbox's intended limits. No public exploit code was identified; the high attack complexity (race-window timing) and dependency on prior renderer compromise plus user interaction make this a chained, opportunistic technique rather than a reliable one-shot.

Monitor Track and reassess. Why: LOW severity (CVSS 0.1-3.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 18, 2026

Access-restriction bypass in Google Chrome's FileSystem component affects all builds prior to 153.0.8010.52 and is only reachable by an attacker who has ALREADY compromised the browser's renderer process through a separate vulnerability, then convinces the victim via social engineering to open a crafted HTML page and finally wins a timing-dependent race condition (CWE-367 TOCTOU). Impact is deliberately narrow: CVSS 3.1 (AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N) reflects no confidentiality or availability loss and only low-integrity impact, with high attack complexity and mandatory user interaction. There is no public exploit identified at time of analysis and no indication of active exploitation; patched builds (153.0.8010.52 and later) are not exploitable, and this is assessed as a low-real-risk browser flaw rather than a standalone attack path.

RemediationAI

Vendor-released patch: Chrome 153.0.8010.52 (or later) - upgrade via chrome://settings/help for automatic updates, or deploy the fixed package through your standard desktop patch pipeline per https://chromereleases.googleblog.com/2026/09/stable-channel-update-for-desktop_0194356994.html; no separate workaround is needed once the fixed build is installed. Because exploitation is chained on an already-compromised renderer plus social engineering, prioritize hardening the prerequisites: keep the sandbox and Site Isolation enabled, patch other renderer-level bugs promptly so the foothold this flaw depends on is harder to obtain, and enforce enterprise policies that restrict or block file-system access from web content (for example the Chrome enterprise policies gating the File System Access API) - the trade-off is that legitimate web apps relying on local file read/write will break and users may seek workarounds, so scope the policy to high-risk populations. Anti-phishing controls and user awareness reduce the UI:R social-engineering step, but they are probabilistic and should not be counted as a fix. Mitigations applied while the update is pending cannot remove the race itself; they only shrink the attack surface, and none is a substitute for installing 153.0.8010.52.

Affected VersionsENISA

Chrome 153.0.8010.52 <153.0.8010.52

Affected Packages

euvd chrome fix: 153.0.8010.52

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 a classic time-of-check-to-time-of-use (TOCTOU) race condition, CWE-367, inside Chrome's FileSystem implementation. Chromium's multi-process architecture places untrusted web content in a sandboxed renderer that must ask the privileged browser process to perform file operations; FileSystem paths and handles are validated at one moment and used at another, and a sufficiently precise attacker who already controls the renderer can change the underlying filesystem state between check and use so that the operation resolves against a different target than the one that was authorized. That is why the vendor's Chromium severity is Medium and the CVSS vector carries AC:H - the window is small, timing-sensitive and unreliable - and why PR:N/UI:R applies: no credentials are needed at the network layer, but a victim must be socially engineered into loading a crafted HTML page. The value of the bug to an attacker is sandbox / system access restriction bypass, i.e. it widens the blast radius of a pre-existing renderer compromise rather than providing an entry point by itself. The NVD reference to issues.chromium.org/issues/498411599 is the upstream engineering record, and the chrome-releases advisory confirms the fix shipped in the Stable channel.

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Severity by source

Vendor (google) PRIMARY 3.1 LOW
AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N
vuln.today AI 3.1 LOW

AC:H for the race window and UI:R for the crafted-page social engineering; PR:N kept because no Chrome auth is bypassed, though a pre-compromised renderer is required; impact limited to I:L filesystem-restriction bypass.

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

Primary rating from Vendor (google).

CVSS VectorVendor: google

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

Lifecycle Timeline

4
CVSS changed
Sep 18, 2026 - 14:22 NVD
3.1 (LOW)
Patch available
Sep 17, 2026 - 22:04 EUVD
CVE Published
Sep 17, 2026 - 21:17 cve.org
UNKNOWN (no severity yet)
CVE Published
Sep 17, 2026 - 21:17 cve.org
LOW 3.1

DescriptionCVE.org

Race condition in FileSystem in Google Chrome prior to 153.0.8010.52 allowed a remote attacker who had compromised the renderer process and leveraged social engineering to bypass system access restrictions via a crafted HTML page. (Chromium security severity: Medium)

Threat Intelligence Overview

EPSS Score
0.2%
Top 91% exploitable
Prevalence
Ubiquitous
Google Chrome desktop, one of the most widely deployed browsers worldwide
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 LOW
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
LOW severity (CVSS 0.1-3.9)
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
High
Technical Impact
Partial

Priority Score

16
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +16
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

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