Google Brotli Google Brotli Unchecked Return Value Vulnerability

Google Brotli contains an unchecked return value vulnerability that allows a remote unauthenticated attacker to corrupt adjacent decoder state memory, disclose sensitive memory contents, cause a denial of service, or potentially execute arbitrary code using a crafted Brotli-compressed stream.

EPSS Exploit Probability82.64%

99.7th percentile

Exploit Maturityactive wild

Active Weaponization

Primary VendorsGoogle

1 product(s) impacted

Ransomware CampaignUnknown

Threat intel association

CVSS v3.1 Vector Breakdown

Comprehensive attack metric decomposition according to FIRST specification

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector (AV)NETWORKRemotely exploitable over network

Attack Complexity (AC)LOWNo specialized access needed

Privileges Required (PR)NONEUnauthenticated exploitation

User Interaction (UI)NONEZero-click / autonomous

Scope (S)UNCHANGEDSecurity authority boundary

Confidentiality (C)HIGHTotal information disclosure

Integrity (I)HIGHTotal compromise of system state

Availability (A)HIGHComplete resource denial

TechOverwatch AI Security Sentinel Analysis

Model: Gemini 2.0 Flash Security Sentinel · Generated: 2026-11-02

Executive Defense Summary

Technical Root Cause Architecture

Vulnerability in Brotli allowing anomalous execution paths when processing untrusted input.

Exploitation Scenario & Attack Chain

Threat actors issue specially crafted requests to the target service to exploit memory corruption or logic flaws.

Enterprise Blast Radius & Lateral Risk

Potential unauthorized access, service disruption, and lateral movement within the perimeter.

Remediation & Defense Playbook

Immediate actionable steps for DevOps, SecOps, and Security Architects

1Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

2Apply security updates according to vendor instructions.

3Ensure network firewalls restrict exposure of administrative ports.

Detection Guidance & Threat Hunting

Monitor endpoint execution logs and network traffic for unusual connections originating from Brotli.

Sigma Detection Rule (SIEM Export)

title: Suspicious CVE-2026-111497 Activity
status: high
logsource:
  category: process_creation
detection:
  selection:
    CommandLine|contains: 'CVE-2026-111497'
  condition: selection

Affected Software & CPE Matrix

Targeted versions, patched releases, and Common Platform Enumerations

Vendor	Product	Affected Versions	Fixed In
Google	Brotli	All vulnerable builds prior to vendor emergency patch	Refer to vendor advisory for patch release

Official Advisories & Authoritative Sources

CISA KEV Catalog Referencehttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2026-111497

cisa

NVD Official Detailhttps://nvd.nist.gov/vuln/detail/CVE-2026-111497

advisory

AI Agent & Security Automation Hub

TechOverwatch provides native machine-readable endpoints for autonomous agents, Cursor, Claude, ChatGPT, and automated patch scanners.

Agent CLI Command (curl):

curl -s https://www.techoverwatch.in/api/vulnerabilities/CVE-2026-111497/raw

Raw Markdown JSON API