Node2Shell evolves into HTTP2Shell, affecting HTTP libraries
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The gist
Security firm Aikido says CVE-2026-111497 now lets attackers run code via Brotli in HTTP libraries.
Patches are incomplete, and common Python packages may not be flagged by audit tools.
Background
CVE-2026-111497 is a flaw in Brotli, a widely used compression library, that lets a crafted Brotli payload trigger memory leaks or arbitrary code execution. OpenAI found the root cause and it was fixed in Brotli's source in February, but no new release shipped, so downstream software kept bundling the vulnerable decoder. Node.js disclosed the bug as "node2shell" on October 21, Python patched it the next day, and on October 23 security firm Aikido Security reported the issue had widened into "HTTP2Shell" — reaching HTTP libraries and apps that decompress Brotli data, including popular Python packages.
How it unfolded
- Feb 2026OpenAI finds the root cause; it is fixed in Brotli's source code, but the security impact isn't known at the time and no newer Brotli release follows.
- Oct 21, 2026Node.js discloses CVE-2026-111497, dubbed "node2shell": a process decompressing attacker-controlled Brotli data can leak memory or run arbitrary code.
- Oct 22, 2026Python releases a security update patching the same flaw; The Hacker News reports no exploitation in the wild as of this date.
- Oct 23, 2026Aikido reports the flaw has evolved into "HTTP2Shell," leaving HTTP libraries and apps open to pre-authorization remote code execution via Brotli decompression.
- Oct 23, 2026Aikido says PyPI packages Brotli (82.8 million monthly downloads) and brotlicffi compile the same vulnerable decoder; fixed versions are Brotli 1.2.1 and brotlicffi 1.2.1.0, but their release notes don't mention the CVE and advisory databases don't map it yet.
- Oct 23, 2026Aikido reports patches available for libbrotli, Python, C++, NodeJS and Envoy, with more coming, and advises updating Brotli libraries or binaries from 1.0.3 through 1.2.0 to 1.0.10, 1.1.1 or 1.2.1.
- Oct 24, 2026Aikido's article is last updated; Cosmic Rundown reports Node2Shell evolved into HTTP2Shell, affecting more HTTP libraries and applications.
Who’s saying what
- Caution
- Aikido Security says the blast radius is significant, fixes aren't yet available for all affected services, and recommends disabling Brotli decoding where no patch exists.
- Expert
- Greg Brockman says it is both an impactful issue and an example of how complicated coordinated patching can be, since the code is integrated into a lot of downstream software.
- Official
- OpenAI says the root cause was fixed in Brotli's source in February, but its security impact wasn't known then and no newer Brotli release followed.
Still unverified
Aikido said other major languages and service applications are likely affected and that it will communicate as soon as it can; it has not yet named them or confirmed patches for them.