CVE-2026-34519

Summary

An attacker who controls the reason parameter when creating a Response may be able to inject extra headers or similar exploits.

Impact

In the unlikely situation that an application allows untrusted data to be used in the response's reason parameter, then an attacker could manipulate the response to send something different from what the developer intended.

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Patch: https://github.com/aio-libs/aiohttp/commit/53b35a2f8869c37a133e60bf1a82a1c01642ba2b