Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/1.1 parser accepts differing duplicate Content-Length headers and uses the last value instead of rejecting the message. When an Ember server is behind a keep-alive intermediary that selects a different occurrence, an unauthenticated attacker can create CL.CL request smuggling that bypasses front-end controls, captures a later user’s headers, or poisons a cache. The shared client parser can also misframe responses from a malicious or compromised upstream when the client acts as a proxy for multiple downstream consumers. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-444"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/69xxx/CVE-2026-69217.json"
}{
"extracted_events": [
{
"introduced": "0"
},
{
"fixed": "0.23.35"
},
{
"introduced": "1.0.0-M1"
},
{
"fixed": "1.0.0-M47"
}
],
"source": [
"AFFECTED_FIELD",
"REFERENCES"
]
}