HTTP Response Splitting Affecting aiohttp package, versions [,3.13.4)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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- published2 Apr 2026
- disclosed1 Apr 2026
- creditDHIRAL2908
Introduced: 1 Apr 2026
NewCVE-2026-34519 (opens in a new tab)How to fix?
Upgrade aiohttp to version 3.13.4 or higher.
Overview
Affected versions of this package are vulnerable to HTTP Response Splitting via the reason parameter in the HTTP response creation process. An attacker can inject unauthorized headers or manipulate the HTTP response by supplying specially crafted input containing carriage return characters.