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Aikido Security reported on Oct. 23 that CVE-2026-111497, first disclosed as the Node.js “Node2Shell” flaw, also affects other runtimes and HTTP-related software that use vulnerable Brotli decoding. Patches are available for several projects, but organizations need to check bundled dependencies and confirm their running systems have been updated.
CVE-2026-111497, a critical flaw in Google’s Brotli decoder first disclosed in Node.js as “Node2Shell,” affects more than Node.js, Aikido Security reported on Oct. 23. The vulnerability may put other runtimes and HTTP applications at risk when they decode attacker-controlled Brotli data; patches were available for several projects at the time of the report, while coverage across affected products remained incomplete.
Aikido described the issue as an out-of-bounds write in Brotli versions 1.0.3 through 1.2.0 across platforms. Its report says a remote attacker who can supply crafted compressed data may corrupt memory, potentially causing a crash or information leak, and may be able to execute code. The source assigns the vulnerability a CVSS v4.0 score of 9.2, classified as critical. These are the reported technical impacts; exposure depends on whether a product uses a vulnerable decoder and processes the attacker-controlled data.
The flaw is relevant to more than an application’s direct dependencies. Aikido said Python HTTP clients including requests, httpx and aiohttp can load Brotli-related packages when installed. It advised users to check for Brotli 1.2.0 or earlier and brotlicffi 1.2.0.x, then upgrade to Brotli 1.2.1 or brotlicffi 1.2.1.0 and rebuild container images containing vulnerable copies. The report cautioned that, as of Oct. 23, advisory databases did not map this CVE to those two PyPI packages, so some dependency scanners might not identify them.
Fixes had been published for several projects by the report’s update time. Listed versions include Node.js 22.23.4, 24.22.1 and 26.12.1; Bun 1.4.4; and supported Envoy releases 1.40.0, 1.39.3, 1.38.6 and 1.37.8. The report also lists fixes for Istio and upstream Brotli. It says Apache and Nginx do not decode Brotli by default, but that does not establish that every configuration or related deployment is unaffected.
Why Brotli Dependencies Matter
The expanded scope matters because Brotli is used to compress web content, and decoding can happen inside runtimes, libraries, HTTP clients, proxies or other applications. Teams that checked only their Node.js versions may miss another vulnerable component, particularly when software bundles or statically links its own Brotli copy. The risk is not determined by a product’s name alone: it depends on its implementation and whether vulnerable decoding is reachable.
The report describes a potential risk in both client and server directions: a malicious client could send crafted compressed data to a vulnerable server, while a malicious server could target a vulnerable client that accepts compressed responses. Aikido said OpenAI reported finding the issue in February and characterized it as unauthenticated remote code execution in both directions. That wording is a reported assessment, not proof that every affected deployment can be exploited in the same way.
For operators, remediation involves more than changing a package declaration. A vulnerable copy may remain in a container image, compiled executable or bundled application after an update. Teams need to update the relevant component, rebuild and redeploy affected artifacts, and verify the versions in running workloads. Where no fix is available, Aikido recommended disabling Brotli decoding if possible until a patched release can be installed.
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Node.js disclosed the issue on Wednesday, Oct. 21, under the name Node2Shell. Python disclosed that Python packages were also affected the following day, according to Aikido’s report. By Friday, Oct. 23, the reported scope had widened to other major languages and HTTP-facing applications, prompting Aikido to describe the broader issue as HTTP2Shell.
The reported root cause is in the shared Brotli decompression code, rather than a problem unique to Node.js. Aikido said the decoder could continue accepting bytes when it should reject the input, allowing data to overflow a working buffer and corrupt memory. OpenAI reportedly found the issue in February and the root-cause code was fixed in the Brotli source then, but the security implications were not recognized at the time and a release carrying the fix did not ship until the current response. Projects that bundle Brotli consequently need their own patched releases.
Aikido’s update listed Apache’s standard mod_brotli as not decoding Brotli by default. It also advises checking other HTTP servers, reverse proxies, gateways and clients according to the decoder they use. For operating-system packages and managed services, the report says to use the vendor’s security update or confirm remediation with the provider; vendors may backport a correction without changing the upstream version number.
““Check if you are decoding Brotli as a dependency within your libraries.””
— Aikido Security
Exposure Depends on Each Product
The exact full list of affected products was not established in the supplied report, which said more patches were coming. A product may use an operating-system library, bundle Brotli, statically link it or avoid Brotli decoding altogether; users need vendor guidance or a component-level check to determine which applies. The report’s statement about Apache and Nginx concerns default decoding behavior and should not be read as a blanket assurance for all configurations or related components.
It is also unclear from the report how many systems are exposed, whether attacks have occurred in the wild, and how often the described memory corruption leads to code execution in specific products. Aikido’s warning describes potential impacts, not confirmed exploitation across all affected software. Scanner gaps reported for the Python packages add uncertainty to automated inventory, while operating-system vendors and managed-service providers may have their own patch status.
Patch, Rebuild and Verify
Organizations should identify where Brotli decoding is enabled, check direct and transitive dependencies, and consult the relevant project or vendor advisory for a fixed release. Aikido lists Brotli 1.2.1 or later for the upstream library, with patched older branches available for some users; runtime-specific version guidance should be followed where the product bundles its own copy. Unsupported release branches should not be treated as a safe long-term destination simply because a fix is listed.
After updating, teams should refresh dependency locks, rebuild images and compiled applications, redeploy, and restart services, then verify the components actually running. Where an update is not yet available, operators should ask the vendor about remediation and consider disabling Brotli decoding if the feature can safely be turned off. The scope and patch status remain developing, so product advisories and supported-release notes will determine the next steps for individual deployments.
Key Questions
What is HTTP2Shell?
HTTP2Shell is the broader name Aikido Security used for the reported spread of CVE-2026-111497 beyond Node.js to other runtimes and HTTP-related software using vulnerable Brotli decoding. Node2Shell was the initial Node.js disclosure name.
What can CVE-2026-111497 allow an attacker to do?
Aikido says crafted Brotli data may cause memory corruption, potentially leading to a crash, information leakage or code execution. The actual exposure and impact depend on the affected product and how it processes compressed data.
Which versions does the report identify as vulnerable?
The report identifies upstream Brotli versions 1.0.3 through 1.2.0 across platforms. It also flags brotlicffi 1.2.0.x and gives package-specific fixed versions; users should check their product vendor’s advisory because bundled copies may have separate release numbers.
Are Apache and Nginx affected?
Aikido says Apache’s standard mod_brotli and Nginx do not decode Brotli by default. That statement does not rule out exposure through other modules, configurations, linked libraries or software in the same deployment; verify the actual setup with the vendor.
What should teams do if they cannot patch immediately?
Check for a vendor update and, where feasible, disable Brotli decoding until a fix is available. Once patched, rebuild and redeploy affected images or executables and confirm that running workloads use the corrected component.
Source: hn
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