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Known exploited vulnerability

CVE-2026-111497

criticalCVSS 4.0 9.2In CISA KEVEPSS 83%Published · Google

The short answer

CVE-2026-111497 affects Google Brotli and is rated critical (CVSS 9.2). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-10-27: attackers are using it, so patch it first. Fixed versions are published for brotli (1.2.1) and brotlicffi (1.2.1.0).

What it is

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.

Weakness: CWE-252, CWE-787.

Severity

9.2 critical

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Exploited (CISA KEV)

Yes, since Oct 27, 2026

Federal due date Nov 10, 2026

EPSS, next 30 days

83%

Higher than 100% of scored CVEs

How it can be exploited

Attack vector
Network
Attack complexity
Low
Attack requirements
Present
Privileges required
None
User interaction
None
Confidentiality impact
High
Integrity impact
High
Availability impact
High

What CISA says to do

Apply 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…

Affected packages and fixed versions

PackageEcosystemFixed inAdvisory
brotliPyPI1.2.1GHSA-9v8h-qqgm-4m35
brotlicffiPyPI1.2.1.0GHSA-9v8h-qqgm-4m35

Is it in your code? Drop your lockfile into the free vulnerability check, or let vulnerability watch check your repository every day and open the upgrade as a pull request.

Affected products

Brotli, Calibre, Calibre ICE, Capital, Cloud Connector Configurator, Common Configurator (CC on IEM), Common Configurator on Device (CC on Edge), COMOS Walkinside, Data Flow Monitoring, Databus Configurator, DataXess Configurator, Designcenter X Essentials. NVD's record lists the exact affected versions.

References

Questions

Is CVE-2026-111497 being exploited?

Yes. CISA added CVE-2026-111497 to its Known Exploited Vulnerabilities catalog on 2026-10-27, with a federal remediation due date of 2026-11-10.

How do I fix CVE-2026-111497?

Upgrade to a fixed version: brotli (PyPI) 1.2.1; brotlicffi (PyPI) 1.2.1.0. CISA's required action: Apply 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…

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Undergoing Analysis. The description is NVD's text, quoted as published.

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