# CVE-2026-111497: Google Brotli buffer overflow in decoder

Source: https://junglewise.ai/threats/cve-2026-111497-a-buffer-overflow-vulnerability-in-the-brotli-decoder-c-dec  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-22. Updated: 2026-10-22  
License: CC BY 4.0 with a link back

CVE-2026-111497 · Severity: critical · CVSS 4 · Exploited in the wild · Published 2026-10-22

Google Brotli is a compression library used in web servers, browsers, and other applications. A buffer overflow flaw in the Brotli decoder allows attackers who send a specially crafted compressed stream to corrupt memory, leak sensitive data, cause the application to crash, or potentially run malicious code—with no authentication required.

Technologies: [Amazon AWS](https://junglewise.ai/threats/technologies/aws), [Google Brotli](https://junglewise.ai/threats/technologies/brotli), [Google Cloud Platform](https://junglewise.ai/threats/technologies/google-cloud-platform), [brotli (PyPI)](https://junglewise.ai/threats/technologies/pypi-brotli). Vendors: [Amazon](https://junglewise.ai/threats/vendors/amazon), [Go](https://junglewise.ai/threats/vendors/go), [Google](https://junglewise.ai/threats/vendors/google), [PyPI](https://junglewise.ai/threats/vendors/pypi).

## Quick answers

**Is CVE-2026-111497 exploited in the wild?** Yes. CVE-2026-111497 is known to be exploited in the wild, first recorded on 27 October 2026. Treat it as urgent.

**How severe is CVE-2026-111497?** Critical severity, with a CVSS score of 4, published 22 October 2026.

**Which products and versions are affected?** github.com/andybalholm/brotli (Go) SEMVER:introduced=0,fixed=1.2.7; Google Brotli 1.0.3 through 1.2.0; Node.js 22.x, 24.x, 26.x (affected versions unspecified); brotli (PyPI) ECOSYSTEM:introduced=0,fixed=1.2.1, ECOSYSTEM:introduced=1.0.3,fixed=1.2.1; and 1 more.

**Is there a fix for CVE-2026-111497?** Yes. github.com/andybalholm/brotli (Go): upgrade to 1.2.7 or later; brotli (PyPI): upgrade to 1.2.1 or later; brotlicffi (PyPI): upgrade to 1.2.1.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-111497 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-111497?** Check whether you run Amazon AWS, github.com/andybalholm/brotli (Go), Google Brotli or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/andybalholm/brotli (Go): upgrade to 1.2.7 or later

  ```sh
  go get github.com/andybalholm/brotli@v1.2.7
  ```

- brotli (PyPI): upgrade to 1.2.1 or later

  ```sh
  pip install "brotli>=1.2.1"
  ```

- brotlicffi (PyPI): upgrade to 1.2.1.0 or later

  ```sh
  pip install "brotlicffi>=1.2.1.0"
  ```


## Technical details

A buffer overflow exists in c/dec/decode.c of the Brotli decoder, triggered when processing a malicious Brotli-compressed stream. The vulnerability is reachable over the network via any application that decompresses untrusted Brotli data, permitting out-of-bounds writes that corrupt adjacent decoder state, disclose memory, or achieve code execution. The flaw affects versions 1.0.3 through 1.2.0 across all platforms.

## Affected products

- Google Brotli 1.0.3 through 1.2.0
- Node.js Node.js 22.x, 24.x, 26.x (affected versions unspecified)

## Identifiers

- CVE-2026-111497
- BIT-BROTLI-2026-111497
- BIT-DOTNET-2026-111497
- BIT-DOTNET-SDK-2026-111497
- BIT-NODE-2026-111497
- BIT-NODE-MIN-2026-111497
- BIT-POWERSHELL-2026-111497
- GHSA-9v8h-qqgm-4m35
- GHSA-c9gr-gmg4-2vqv
- GO-2026-6888
- PYSEC-2026-4322
- PYSEC-2026-4323

## Timeline

- 2026-10-21: disclosed

## References

- [https://nodejs.org/en/blog/vulnerability/october-2026-security-releases](https://nodejs.org/en/blog/vulnerability/october-2026-security-releases)

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