Vulnerability report

Exploitation attempts observed Confirmed confidence In CISA KEV

CVE-2026-111497

Out-of-Bounds Write in Google Brotli Decoder

Google / Brotli · affected before 1.0.10

Watch CVE-2026-111497 Browse KEV feed
Severity
CVSS 9.2 · Critical
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
55.5%
First observed
27 Oct 2026
Last observed
27 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-111497 is an unauthenticated Out-of-Bounds Write in Google Brotli Decoder. A buffer overflow vulnerability in the Brotli decoder (c/dec/decode.c) in Google Brotli versions 1.0.3 through 1.2.0 on all platforms...

Have exploitation attempts been observed?

Yes. Previdian sensors have observed 1 exploitation attempt, 1 unique attacker IP, and 1 country targeting CVE-2026-111497. First observed Oct 27, 2026. Listed in CISA KEV. Also reported by third-party sources. Confidence is confirmed.

Who is affected?

Google / Brotli affected before 1.0.10.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

Out-of-Bounds Write in Google Brotli Decoder

A buffer overflow vulnerability in the Brotli decoder (c/dec/decode.c) in Google Brotli versions 1.0.3 through 1.2.0 on all platforms 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.

Users need to update any Brotli libraries or binaries between 1.0.3 through 1.2.0 to the latest available version: 1.0.10 or 1.1.1 or 1.2.1.

Google Affected
Brotli github.com/google/brotli
Before 1.0.10 Before 1.1.1 Before 1.2.1
View vendor advisory (opens in new tab)
Published
22 Oct 2026
Attempts Observed Since
27 Oct 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

cisa

CVE References

  • CVE Record CVE.org · CVE Record https://www.cve.org/CVERecord?id=CVE-2026-111497
  • Patch — nodejs.org nodejs.org · Patch https://nodejs.org/en/blog/vulnerability/october-2026-security-releas...
  • GitHub — andybalholm/brotli github.com · Third-Party Advisory https://github.com/andybalholm/brotli/releases/tag/v1.2.7

Exploitation evidence

Evidence of exploitation attempts

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploitation attempts observed in the wild

Previdian sensor

Recorded 27 Oct 2026

Previdian sensors observed exploitation attempts targeting this vulnerability before a third-party report.

Exploitation attempts observed

Previdian sensor

First observed 27 Oct 2026

Previdian sensors observed exploitation attempts targeting this vulnerability.

Proof of concept available

GitHub

Recorded 22 Oct 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
CISA First 2026-10-27 20:01 UTC
Previdian Sensors 2026-10-27 20:05 UTC
Tenable Blog 2026-10-27 20:20 UTC
The Hacker News 2026-10-28 06:33 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

Previdian Sensor Observations

Previdian sensor observations are exploitation attempts targeting this vulnerability. They do not show that the target was vulnerable or that the attempt succeeded. The cards and chart show volume, unique attackers, and daily activity.

1

Attempts observed

1

Unique attacker IPs

1

Attacker countries

US

1

Sensors observed

CVE-2026-111497 exploitation attempts over the last 7 days

Daily events observed by Previdian sensors

Updated 28 Oct 2026

0
0
0
0
0
1
0
22 Oct 23 Oct 24 Oct 25 Oct 26 Oct 27 Oct 28 Oct

First observed 27 Oct 2026 · Last observed 27 Oct 2026

Pro adds sensor region and window summaries. Enterprise adds raw IPs, paths, User-Agents, and payloads.

Start 14-day Pro trial

Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
1
1
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

Learn about Pro API access

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

9.2 Critical

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

EPSS

55.5%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Unchecked Return Value CWE-252 Out-of-bounds Write CWE-787

Recent mention · The Hacker News

Adobe Commerce PolyShell Attacks Breach Hundreds of Stores as Brotli Exploit Traffic Emerges

Ravie LakshmananOct 28, 2026Vulnerability / Web Security The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Tuesday added two vulnerabilities impacting Adobe Commerce and Magento, and Google's Brotli decoder library to its Known Exploited Vulnerabilities...

Read full advisory

All Mentions

Recent mention · SOCRadar

Node2Shell: Brotli Flaw Hits Python Packages

SOCRadar · 26 Oct 2026

The Node2Shell Brotli flaw (CVE-2026-111497), disclosed alongside Node.js fixes on October 21, 2026, also reaches Python through the PyPI Brotli and brotlicffi packages. Both compile Google’s vulnerable Brotli C decoder, and popular HTTP clients such as requests, httpx and aiohttp use them to decompress responses automatically once they are installed. That makes exposure easy to […]

Recent mention · FortiGuard

Multiple Node.js CVEs

FortiGuard · 26 Oct 2026

CVSSv3 Score: 9.8 CVE-2026-105482 - (high)This vulnerability affects Node.js 26.x, 24.x, and 22.x.CVE-2026-105483 - (high)This vulnerability affects Node.js 26.x and 24.x.CVE-2026-106069 - (high)This vulnerability affects Node.js 26.x, 24.x, and 22.x.CVE-2026-111497 - (high)A flaw in Node.js can cause Node.js Brotli decoder out-of-bounds write permits remote code execution.This vulnerability affects Node.js 26.x, 24.x, and 22.x.CVE-2026-105481 - (medium)This vulnerability affects Node.js 26.x, 24.x, and 22.x.CVE-2026-106072 - (medium)This vulnerability affects Node.js 26.x, 24.x,...

Recent mention · Wiz

Broccoli2shell: Everything You Need To Know About The Critical Brotli Decoder Vulnerability

Wiz · 25 Oct 2026

Detect and mitigate CVE-2026-111497, a critical Brotli decoder vulnerability enables remote code execution.

Recent mention · The Hacker News

OpenAI AI Agents Demonstrate VM Escapes and Secret Cross-Sandbox Communication

The Hacker News · 25 Oct 2026

Ravie LakshmananOct 25, 2026Artificial Intelligence / Cybersecurity OpenAI has announced plans to conduct frontier model training with no live internet access, as it resumes reinforcement learning (RL) training and internal inference of its most advanced AI models. "Based on the current state of alignment research, monitoring systems, and the security of internet infrastructure, we believe the responsible approach is to conduct frontier model training with no internet access," the artificial intelligence (AI) company said. "We've implemented this policy and will maintain it until advances...

Recent mention · The Hacker News

Brotli Decoder Flaw Behind Node.js RCE Also Affects Bun, Python and Other Widely Used Software

The Hacker News · 24 Oct 2026

Swati KhandelwalOct 24, 2026Vulnerability / Web Security A memory-corruption flaw in Google's Brotli decoder sits in many programs that unpack Brotli-compressed data, among them Bun, the Python Brotli and brotlicffi packages, and Envoy proxies set up to decompress Brotli. Tracked as CVE-2026-111497, the flaw allows crafted compressed data to overwrite past the end of a buffer and corrupt a program's memory, potentially causing a crash, a memory leak, or the execution of attacker-controlled code. Imperva researchers have shown that code can run on one unpatched Node.js build. The same has...

Recent mention · F5 Security Advisories

K000163874: Multiple Node.js vulnerabilities

F5 Security Advisories · 23 Oct 2026

Security Advisory Description CVE-2026-105481 This candidate has been reserved by a CVE Numbering Authority (CNA). This record will be updated by the assigning CNA once details are available. Learn more about the Reserved state here. CVE-2026-105482 This candidate has been reserved by a CVE Numbering Authority (CNA). This record will be updated by the assigning CNA once details are available. Learn more about the Reserved state here. CVE-2026-105483 This candidate has been reserved by a CVE Numbering Authority (CNA). This record will be updated by the assigning CNA once details are...

Recent mention · The Hacker News

Researchers Demonstrate Node2Shell RCE Exploit on Node.js Build Using Crafted Brotli Data

The Hacker News · 23 Oct 2026

Malicious Brotli data can make an application on an official build of Node.js run attacker-supplied code, security researchers at Imperva have demonstrated. Their "Node2Shell" proof of concept ran code on the official Node.js 24.22.0 image for Linux arm64, with no debugger or custom build, by feeding crafted data to the bundled Brotli decoder (CVE-2026-111497). Node.js disclosed the flaw

Recent mention · Github Advisory Database (PIP)

[brotlicffi] Brotli: Out-of-bounds write in the Brotli decoder ("Node2Shell") also affects the PyPI Brotli package

Github Advisory Database (PIP) · 22 Oct 2026

A buffer overflow vulnerability in the Brotli decoder (c/dec/decode.c) in Google Brotli versions 1.0.3 through 1.2.0 on all platforms 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. Users need to update any Brotli libraries or binaries between 1.0.3 through 1.2.0 to the latest available version: 1.0.10 or 1.1.1 or...

Recent mention · The Hacker News

Node.js Brotli Decoder Bug Could Allow Remote Code Execution in All Supported Versions

The Hacker News · 22 Oct 2026

Swati KhandelwalOct 22, 2026Vulnerability / Web Security Node.js released security updates on October 21 for its three supported release lines, 22.x, 24.x and 26.x, fixing 10 flaws. The most serious is a bug in the Brotli decompression code that Node.js bundles, which the project says can allow remote code execution, meaning an attacker could run code of their choosing on the affected system. Each supported line has one fixed version: 22.23.4 and 24.22.1 on the long-term support lines, and 26.12.1 on the current line. Node.js 20.x and earlier have reached end of life and will not receive...

Recent mention · Tenable Blog

php2shell (CVE-2026-109618, CVE-2026-109619): Frequently asked questions about critical PHP remote code execution vulnerabilities

Tenable Blog · 21 Oct 2026

Two critical PHP vulnerabilities could lead to unauthenticated remote code execution. Patches are available for supported PHP 8.x branches, and exploitation attempts began before public disclosure.Change logUpdate October 26: CISA added CVE-2026-109618 and CVE-2026-109619 to its KEV catalog. Added details on a regression in PHP 8.4.27 and 8.5.12 and on PHP's October 23 session upload progress advisory. Added a note on restarting PHP services after updating. Added Adel Karimi's report of successful exploitation against honeypot servers and Trail of Bits' report of working exploits against...

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

Hika-sec/http2shell-CVE-2026-111497

github · Created 2026-10-25 18:05:02 UTC · 3 stars · AI assessment 82%

PoC for CVE-2026-111497, a buffer overflow in Google Brotli 1.0.3–1.2.0 that may cause memory corruption, data disclosure, DoS, or RCE when processing crafted compressed data.

Arkango/CVE-2026-111497

github · Created 2026-10-23 14:34:49 UTC · 0 stars · AI assessment 82%

CVE-2026-111497 (Node2Shell) — Node.js Brotli decoder OOB heap write. Independent research: exploit code, Docker labs, Express RCE gap analysis.

TheFool-TAROT/CVE-2026-111497-brotli-pwn

github · Created 2026-10-22 16:30:53 UTC · 0 stars · AI assessment 84%

CVE-2026-111497: Node.js Brotli decoder OOB write — analysis, PoC, Docker lab

dimasma0305/CVE-2026-111497-POC

github · Created 2026-10-22 04:08:28 UTC · 1 stars · AI assessment 86%

Reproducible local Brotli decoder proof for CVE-2026-111497 with a self-checking tuned RCE harness

CVE Record exploit — imperva.com

cve · Created Unknown

Timeline

From disclosure to observed exploitation attempts

  1. 06:33 UTC

    KEV confirmed by The Hacker News

    Exploitation attempts reported by an external source

  2. 20:20 UTC

    KEV confirmed by Tenable Blog

    Exploitation attempts reported by an external source

  3. 20:01 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  4. 20:01 UTC

    Indicator of compromise added

    Indicators of compromise recorded

  5. 20:01 UTC

    Observed by Previdian sensors

    Previdian sensors observed exploitation attempts targeting this vulnerability.

  6. 14:20 UTC

    Added to the Previdian watchlist

    Pro and Enterprise Watch users had 5 days of early warning before CISA KEV. Also 5 days before Previdian confirmed it as a KEV.

  7. 13:35 UTC

    CVE published

    Vulnerability disclosed publicly

  8. 04:08 UTC

    Public PoC available

    Public proof-of-concept code published

  9. 09:58 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

Start 14-day Pro trial Read API docs
  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-111497

Sample API response 
{
  "cve_id": "CVE-2026-111497",
  "confidence": "Confirmed",
  "cvss_score": 9.2,
  "cvss_estimated": false,
  "epss_score": 0.55483,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 1, "sensors": 1 }
}