CVE-2026-69215

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, The CookieJar client middleware uses unanchored substring checks instead of RFC 6265 domain and path matching when deciding whether to attach a stored cookie. A cookie for example.com can consequently be sent to an...

CVE-2026-69206

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, DigestAuth replay protection records lastNc plus one instead of the highest nonce-count value it has accepted. When a legitimate client sends noncontiguous nc values because of parallel or retried requests, the stored...

CVE-2026-69210

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, WebSocket FrameTranscoder.bodyLength rejects extended payload lengths above Integer.MAXVALUE but permits negative 64-bit lengths. A remote client that completes a WebSocket handshake through an Ember server can send su...

CVE-2026-69205

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HeaderP.parse uses a case-sensitive substring test for the Transfer-Encoding value and decodes header bytes with the platform default charset. Values such as Chunked are not recognized, values such as notchunke...

CVE-2026-69203

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, An Ember server with HTTP/2 enabled through withHttp2 does not enforce SETTINGSMAXCONCURRENTSTREAMS for peer-created streams. One unauthenticated connection can open an unbounded number of streams, each retaining...

CVE-2026-69202

Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, Ember’s HTTP/2 flow-control window is replenished according to bytes received from the network rather than bytes consumed by the application, while each stream stores DATA in an unbounded channel. A hostile peer can...

GHSA-GQ9P-F254-H286 Http4s: Ember HTTP/2 buffers a frame's declared payload before checking SETTINGS_MAX_FRAME_SIZE

Summary An unauthenticated peer can make Ember's HTTP/2 read loop hold 16 MiB of a single frame in memory on a connection where Ember advertised a 16 KiB limit. The declared length is readable from the frame's first 9 bytes, but it is not compared against SETTINGSMAXFRAMESIZE until the whole...

Http4s: ResourceService and Webjar Service path escape via percent-encoded separators

The static content handlers ResourceService and WebjarService URL decode each path segment and then reject only segments that are exactly "", ".", or "..". A percent-encoded separator %2F lets an attacker smuggle a ../ segment past that filter and escape the configured base, reading resources tha...

GHSA-CRQ5-92J2-J7WV Http4s: ResourceService and Webjar Service path escape via percent-encoded separators

The static content handlers ResourceService and WebjarService URL decode each path segment and then reject only segments that are exactly "", ".", or "..". A percent-encoded separator %2F lets an attacker smuggle a ../ segment past that filter and escape the configured base, reading resources tha...

GHSA-CP4Q-FQW9-4HF6 Http4s Ember HTTP/2: unbounded continuation frame accumulation

When Ember receives an HTTP/2 HEADERS or PUSHPROMISE frame without the ENDHEADERS flag, it buffers the header block fragment and waits for subsequent CONTINUATION frames. These accumulate unbounded until the connection closes. Impact A remote, unauthenticated peer can exhaust the heap on any Embe...

Http4s Ember HTTP/2: unbounded continuation frame accumulation

When Ember receives an HTTP/2 HEADERS or PUSHPROMISE frame without the ENDHEADERS flag, it buffers the header block fragment and waits for subsequent CONTINUATION frames. These accumulate unbounded until the connection closes. Impact A remote, unauthenticated peer can exhaust the heap on any Embe...

Http4s: Ember chunk parser lenience (TE.TE request smuggling)

Summary Ember's chunk decoder parses the size token leniently: it strips leading and trailing whitespace and accepts a leading + or - sign. RFC9112 §7.1 defines chunk-size = 1HEXDIG. An intermediary that parses the chunk boundary differently or rejects it will disagree with Ember on request...

GHSA-JRPM-956J-96JG Http4s: Ember chunk parser lenience (TE.TE request smuggling)

Summary Ember's chunk decoder parses the size token leniently: it strips leading and trailing whitespace and accepts a leading + or - sign. RFC9112 §7.1 defines chunk-size = 1HEXDIG. An intermediary that parses the chunk boundary differently or rejects it will disagree with Ember on request...

Http4s: CookieJar middleware matches by substring, leaking cookies cross-origin

The CookieJar client middleware decides whether to attach a cookie to an outgoing request using an unanchored substring test on the host and path, instead of the domain match specified by RFC6265 5.1.3. A cookie stored for example.com is therefore sent to any host whose name merely contains...

GHSA-GRH8-3P95-F9RR Http4s: CookieJar middleware matches by substring, leaking cookies cross-origin

The CookieJar client middleware decides whether to attach a cookie to an outgoing request using an unanchored substring test on the host and path, instead of the domain match specified by RFC6265 5.1.3. A cookie stored for example.com is therefore sent to any host whose name merely contains...

Http4s: CookieJar middleware accepts arbitrary Set-Cookie domain

When processing a Set-Cookie from a response, the CookieJar client middleware trusts the server-supplied Domain attribute verbatim, with no check that it domain-matches the host that sent the cookie RFC6265 §5.3 step 6 and no public suffix check. A malicious or compromised server can therefore...

GHSA-WV64-J4FQ-5F9X Http4s: CookieJar middleware accepts arbitrary Set-Cookie domain

When processing a Set-Cookie from a response, the CookieJar client middleware trusts the server-supplied Domain attribute verbatim, with no check that it domain-matches the host that sent the cookie RFC6265 §5.3 step 6 and no public suffix check. A malicious or compromised server can therefore...

GHSA-8F3Q-3JMV-7PRW Http4s Ember HTTP/2 has an unbounded outbound frame queue

Ember's HTTP/2 connection serializes all outgoing frames through a single unbounded queue drained by one writer fiber writeLoop. When the write side stalls, any frames the connection keeps producing accumulate in that queue without limit. The peer can drive this cheaply because the connection emi...

Http4s Ember HTTP/2 has an unbounded outbound frame queue

Ember's HTTP/2 connection serializes all outgoing frames through a single unbounded queue drained by one writer fiber writeLoop. When the write side stalls, any frames the connection keeps producing accumulate in that queue without limit. The peer can drive this cheaply because the connection emi...

Http4s: DigestAuth nonce map grows unbounded

The DigestAuth server middleware's stale-nonce cleanup uses an inverted comparison: it removes fresh nonces and stops at the first stale one. Because a new nonce is created for every unauthenticated challenge, an attacker can drive the nonce map to grow without bound until the JVM runs out of hea...