CVE-2021-21299High· 8.1▾ TwilightMultiple Transfer-Encoding headers misinterprets request payload
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 44.6 · likelihood 0.9 · exploitation 0
Need a working PoC? Pro members can cast a request and our team develops one — it lands right here.
Exploit-prediction probability, daily snapshots since Aug 1.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
4.8%
Last analysed / modified upstream
4.8 → 8.1
medium → high
hyper's HTTP server code had a flaw that incorrectly understands some requests with multiple transfer-encoding headers to have a chunked payload, when it should have been rejected as illegal. This combined with an upstream HTTP proxy that understands the request payload boundary differently can result in "request smuggling" or "desync attacks".
hyper >= 0.14.0-0, < 0.14.3Upgrade to a patched release:
hyper 0.14.3Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.