CVE-2026-34519Low▾ SunlitAIOHTTP has HTTP response splitting via \r in reason phrase
▾ Sunlit zone — Low / medium · no exploitation signal
impact 13.8 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Jul 13.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
0.3%
Last analysed / modified upstream
An attacker who controls the reason parameter when creating a Response may be able to inject extra headers or similar exploits.
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.
Patch: https://github.com/aio-libs/aiohttp/commit/53b35a2f8869c37a133e60bf1a82a1c01642ba2b
aiohttp < 3.13.4Upgrade to a patched release:
aiohttp 3.13.4Connected by shared product, vendor, weakness, or advisory.
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