AWS sets staged Lambda fixes for a Brotli flaw that can expose memory or run code

AWS maps the Brotli flaw to managed and customer-controlled components

AWS published an Important security bulletin on October 28 for CVE-2026-111497, an out-of-bounds write in the native Brotli decoder. A program that decompresses specially constructed Brotli input can crash, disclose process memory or allow code execution. AWS says the Lambda service itself is not affected, but supported Node.js and .NET runtimes, customer-supplied libraries and several deployment formats need different fixes.

The Node.js project rates the issue high severity for versions 22, 24 and 26 when an application passes attacker-controlled Brotli data to its decompression APIs. That condition matters: the advisory does not say every Node.js workload is automatically exploitable. Teams still need to identify where untrusted compressed input is decoded and which runtime or library actually handles it.

The update path depends on how the workload is packaged

AWS marks the Node.js 22, 24 and 26 Lambda container base images updated, so container users must rebuild from the current image and redeploy. For managed ZIP runtimes, AWS lists two Node.js rollout phases ending October 30. Its affected .NET schedule extends through October 31. The bulletin provides runtime-version markers for Node.js 22 and 24 so operators can verify an update in the INIT_START line of a cold-start log instead of relying on an application version string.

App Runner's managed Node.js runtime was updated across AWS Regions on October 26, but services not deployed since then need one redeployment; a service pinned to an older runtime must change the pin first. AWS says Amplify Hosting compute will apply supported Node.js 22 and 24 updates automatically, while applications on earlier releases should move to a supported version.

Bundled libraries and retired runtimes remain an owner responsibility

AWS advises customers to replace deprecated Node.js 18 and 20 runtimes and to inventory function layers, dependencies and custom images for separate Brotli copies. Where a vendor fix is not yet available, its temporary recommendation is to disable Brotli decoding. The bulletin is still being updated, and CGH has not tested the flaw, confirmed exploitation in an AWS workload or verified every regional rollout. Operators should recheck the source before treating a scheduled phase as complete.