Do not download the archive files generated by GitHub. They do not work. Please download the signed and versioned tar balls, such as nghttp2-1.68.1.tar.gz.

This release includes security advisory.

Security Advisory

CVE-2026-27135: Denial of service: Assertion failure due to the missing state validation

For more information, read the security advisory.

Do not download the archive files generated by GitHub. They do not work. Please download the signed and versioned tar balls, such as nghttp2-1.68.0.tar.gz.

lib

This release adds more glitch counters for the unexpected builtin extension frames.

h2load

This release changes the default QUIC window-bits to 24 to reduce the fragmentation on huge packet losses.

nghttpd

This release makes the supported groups configurable with --groups option.

nghttpx

TLSv1.0 and TLSv1.1 support has been dropped.

ML-DSA certificates are now selected over ECDSA and RSA. ML-DSA certificates are supported by OpenSSL and wolfSSL TLS backends.

Certificate selection based on client capability is extended to wolfSSL and BoringSSL.

--group option has been added. --ecdh-curves option has been deprecated, and if it is used, it is treated as if --group option is used.

Do not download the archive files generated by GitHub. They do not work. Please download the signed and versioned tar balls, such as nghttp2-1.67.1.tar.gz.

lib

Remove session_update_glitch_ratelim call from session_handle_invalid_stream2. Because that makes error handling quite difficult because it might be called in the nested function calls, and that might lead to the unexpected result. It seems to me that this was accidentally added.

Do not download the archive files generated by GitHub. They do not work. Please download the signed and versioned tar balls, such as nghttp2-1.67.0.tar.gz.

lib

This release adds nghttp2_rand_callback, and the internal hash map is initialized with the seed sampled from this callback.

Some stream errors are now promoted to the connection errors. This means that an event that previously just resets a single stream now closes a connection entirely. The promoted errors are mostly implementation errors.

We have some contradictory specifications around nghttp2_on_invalid_header and nghttp2_on_invalid_header2 callbacks. nghttp2_on_invalid_header says that if it is omitted, a stream is reset. Meanwhile, nghttp2_on_invalid_header2 says that if it is omitted, invalid field is silently ignored. In actual implementation, if both omitted, we treat it as stream error. In practice, it is often required not to bail out if invalid header is received. In this change, if both callbacks are omitted, invalid field is silently ignored as the documentation of nghttp2_on_invalid_header2 says.

The “glitch” counter has been introduced. Any suspicious activity such as DATA frames to a stream which does not exist are counted to so called “glitch” counter. If it increases more than the configured rate, GOAWAY is sent and the connection is closed.

Do not download the archive files generated by GitHub. They do not work. Please download the signed and versioned tar balls, such as nghttp2-1.66.0.tar.gz.

lib

nghttp2_submit_rst_stream now does not add RST_STREAM frame more than once.

src

The support for the draft HTTP/2 ALPNs (e.g., h2-14, h2-16) have been removed.

doc

This release fixes build failure with rubydomain namespace.

h2load

QUIC is now enabled with OpenSSL >= 3.5.0.

nghttpx

QUIC is now enabled with OpenSSL >= 3.5.0.

The bug in Forwarded By parameter value that exhibits when a frontend socket listens on wildcard address has been fixed.

The rate limiting for incoming QUIC traffic has been implemented. --read-rate and --read-burst options are now applied to QUIC connection as well.

Each worker thread has its listening TCP sockets.

The usage counts of a weight group are preserved after replacing backends with backendconfig API if the name and weight of the groups under the pattern have not changed.

OCSP stapling feature has been removed.

TLS session cache via memcached has been removed.

nghttpd

Support for SSLKEYLOGFILE has been added.

Do not download the archive files generated by GitHub. They do not work. Please download the signed and versioned tar balls, such as nghttp2-1.65.0.tar.gz.

lib

RFC 7540 Priorities implementation has been removed. Here is the summary of the behavioral changes in the public API functions:

• nghttp2_session_change_stream_priority: This function is noop. It always returns 0.
• nghttp2_session_create_idle_stream: This function is noop. It always returns 0.
• nghttp2_submit_request: pri_spec is ignored.
• nghttp2_submit_request2: pri_spec is ignored.
• nghttp2_submit_headers: pri_spec is ignored.
• nghttp2_submit_priority: This function is noop. It always returns
• nghttp2_stream_get_parent: This function always returns NULL.
• nghttp2_stream_get_next_sibling: This function always returns NULL.
• nghttp2_stream_get_previous_sibling: This function always returns NULL.
• nghttp2_stream_get_first_child: This function always returns NULL.
• nghttp2_stream_get_weight: This function always returns NGHTTP2_DEFAULT_WEIGHT.
• nghttp2_stream_get_sum_dependency_weight: This function always returns 0.

nghttp2_option_set_server_fallback_rfc7540_priorities and nghttp2_option_set_no_closed_streams have also been deprecated, and have no effect.

QNX build support has been added.

cmake

Disable src tests if BUILD_TESTING is OFF.

src

url-parser has been replaced with urlparse.

h2load

Account for bytes on closing connections.

nghttp

nghttp now does not create the initial dependency tree. --no-dep and --no-rfc7540-pri options have been deprecated.

nghttp now always sends NGHTTP2_SETTINGS_NO_RFC7540_PRIORITIES HTTP/2 setting. --extpri option has been added to set priority for a given URI.

nghttpd

This change deprecates --no-rfc7540-pri option. SETTINGS_NO_RFC7540_PRIORITIES HTTP/2 setting is now always sent.

Do not download the archive files generated by GitHub. They do not work. Please download the signed and versioned tar balls, such as nghttp2-1.64.0.tar.gz.

lib

The internal :authoriy and host field value validation now treats @ as invalid. nghttp2_check_authority still treats it as a valid character.

cmake

This release fixes c-ares v1.34.0 version detection failure.

h2load

This release fixes race condition on h1 connection close.

It also fixes UDP datagram send/recv metric.

Do not download the archive files generated by GitHub. They do not work. Please download the signed and versioned tar balls, such as nghttp2-1.63.0.tar.gz.

lib

Compile error emitted by old compilers is suppressed.

nghttp2.h undefines NGHTTP2_NO_SSIZE_T if BUILDING_NGHTTP2 is defined.

src

wolfSSL support has been added.

Do not download the archive files generated by GitHub. They do not work. Please download the signed and versioned tar balls, such as nghttp2-1.62.0.tar.gz.

This release includes security advisory.

Security Advisory

CVE-2024-28182: Reading unbounded number of HTTP/2 CONTINUATION frames to cause excessive CPU usage

For more information, read the security advisory.

For other changes, refer to v1.61.0 release notes.

Do not download the archive files generated by GitHub. They do not work. Please download the signed and versioned tar balls, such as nghttp2-1.61.0.tar.gz.

lib

RFC 7540 priorities (aka stream dependencies) APIs have been deprecated. They work just like before, but in the future release after the end of 2024, the functionality is removed, and the deprecated APIs start behaving differently. See the API documentation for details. RFC 7540 priorities have been deprecated by RFC 9113. Consider migrating RFC 9218 extensible prioritization scheme.

The APIs that use ssize_t, including structs and callback functions, have been deprecated. New APIs that use nghttp2_ssize are introduced as a replacement. The usage of ssize_t is problematic for several reasons. Some platforms do not define ssize_t. The minimum value of ssize_t that POSIX requires is -1 which makes nghttp2 error code out of range. nghttp2_ssize is an alias of ptrdiff_t that is in C standard and covers our error code range.

New code should use new nghttp2_ssize APIs. The existing applications should consider migrating to new APIs.

The deprecated ssize_t APIs continue to work for backward compatibility.

Here is the summary of the deprecated APIs and their replacements:

Callback functions:

• nghttp2_data_source_read_callback => nghttp2_data_source_read_callback2
• nghttp2_data_source_read_length_callback => nghttp2_data_source_read_length_callback2
• nghttp2_pack_extension_callback => nghttp2_pack_extension_callback2
• nghttp2_recv_callback => nghttp2_recv_callback2
• nghttp2_select_padding_callback => nghttp2_select_padding_callback2
• nghttp2_send_callback => nghttp2_send_callback2

Structs:

• nghttp2_data_provider => nghttp2_data_provider2

Functions:

• nghttp2_hd_deflate_hd => nghttp2_hd_deflate_hd2
• nghttp2_hd_deflate_hd_vec => nghttp2_hd_deflate_hd_vec2
• nghttp2_hd_inflate_hd2 => nghttp2_hd_inflate_hd3
• nghttp2_pack_settings_payload => nghttp2_pack_settings_payload2
• nghttp2_session_callbacks_set_data_source_read_length_callback => nghttp2_session_callbacks_set_data_source_read_length_callback2
• nghttp2_session_callbacks_set_pack_extension_callback => nghttp2_session_callbacks_set_pack_extension_callback2
• nghttp2_session_callbacks_set_recv_callback => nghttp2_session_callbacks_set_recv_callback2
• nghttp2_session_callbacks_set_select_padding_callback => nghttp2_session_callbacks_set_select_padding_callback2
• nghttp2_session_callbacks_set_send_callback => nghttp2_session_callbacks_set_send_callback2
• nghttp2_session_mem_recv => nghttp2_session_mem_recv2
• nghttp2_session_mem_send => nghttp2_session_mem_send2
• nghttp2_submit_data => nghttp2_submit_data2
• nghttp2_submit_request => nghttp2_submit_request2
• nghttp2_submit_response => nghttp2_submit_response2

For those applications that do not want to see ssize_t in nghttp2.h header file at all, define NGHTTP2_NO_SSIZE_T macro before including nghttp2.h. It hides all ssize_t APIs.

build

cmake build and install trees are now fixed.

The following dependencies have been updated:

• ngtcp2
• nghttp3

CUnit has been replaced with ngtcp2/munit. munit is pulled via git submodule.

The flags to build applications with libbrotli have been added.

third-party

llhttp has been updated.

mruby is updated to v3.3.0.

h2load

--sni option has been added.

src

The certificate compression support with boringssl (or aws-lc) and libbrotli has been added.

lib

This release adds API to get and parse RFC 9218 priority.

nghttp2_select_next_protocol() has been deprecated. Use nghttp2_select_alpn() instead.

build

The following dependencies have been updated:

• ngtcp2
• libbpf

h2load

h2load now considers all h2 HEADERS when counting bytes and recording TTFB.

This release fixes the bug that TTFB is not recorded if h3 stream has no data.

h2load now ignores 1xx status code.

IPv6 address is now enclosed by square brackets when set in :authority header field.

nghttpx

This release adds SSL_CTX_set_recv_max_early_data() call which OpenSSL requires.

__FILE_NAME__ macro is preferred if available.

nghttpx now propagates stream priority from backend to frontend.

This release fixes the bug that nghttpx sends QUIC RESET_STREAM when it receives RESET_STREAM from client.

src

This release drops old OpenSSL (< 1.1.1) support.

Now bundled applications can be built with aws-lc.

lib

This release fixes build issues with cygwin and mingw.

build

This release speeds up warning option detection with cmake.

The following dependencies have been updated:

• ngtcp2
• nghttp3

third-party

neverbleed has been updated.

nghttpx

This release introduces stricter transfer-encoding checks.

integration

Enable http3 test with cmake.

This release includes security advisory.

Security Advisory

CVE-2023-44487: HTTP/2 Rapid Reset

For more information, read the security advisory.

lib

This release has a fix to mitigate CVE-2023-44487: HTTP/2 Rapid Reset. It has reasonable amount of default budgets for incoming RST_STREAM frames. Application can tune the rate limit by using nghttp2_option_set_stream_reset_rate_limit. It can also implement its own rate limit by implementing nghttp2_on_frame_recv_callback and check RST_STREAM frame.

nghttpx

This release fixes the bug that --single-process does not work. It also fixes the bug that TLS connection is not rate limited.

build

The following dependencies have been updated:

• ngtcp2
• nghttp3
• BoringSSL
• quictls
• libbpf

third-party

llhttp has been updated.

nghttpx

Rework is done in functions that send ECN bits.

--frontend-quic-congestion-controller=bbr2 has been renamed to --frontend-quic-congestion-controller=bbrv2.

nghttpx, h2load

Fix issue that CMSG_DATA does not necessarily return an aligned pointer.

This release includes security advisory.

Security Advisory

CVE-2023-35945: HTTP/2 memory leak in nghttp2 codec

For more information, read the security advisory.

This CVE was filed by envoyproxy/envoy project, and has already been made public, and we did not take usual security procedure. See below why.

lib

This release fixes memory leak that happens when PUSH_PROMISE or HEADERS frame cannot be sent, and nghttp2_on_stream_close_callback fails with a fatal error. For example, if GOAWAY frame has been received, a HEADERS frame that opens new stream cannot be sent.

This issue has already been made public via CVE-2023-35945 issued by envoyproxy/envoy project. During embargo period, the patch to fix this bug was accidentally submitted to nghttp2/nghttp2 repository. And they decided to disclose CVE early. I was notified just 1.5 hours before disclosure. I had no time to respond.

PoC described in CVE is quite simple, but I think it is not enough to trigger this bug. While it is true that receiving GOAWAY prevents a client from opening new stream, and nghttp2 enters error handling branch, in order to cause the memory leak, nghttp2_session_close_stream function must return a fatal error. nghttp2 defines 2 fatal error codes:

• NGHTTP2_ERR_NOMEM
• NGHTTP2_ERR_CALLBACK_FAILURE

NGHTTP2_ERR_NOMEM, as its name suggests, indicates out of memory. It is unlikely that a process gets short of memory with this simple PoC scenario unless application does something memory heavy processing.

NGHTTP2_ERR_CALLBACK_FAILURE is returned from application defined callback function (nghttp2_on_stream_close_callback, in this case), which indicates something fatal happened inside a callback, and a connection must be closed immediately without any further action. As nghttp2_on_stream_close_error_callback documentation says, any error code other than 0 or NGHTTP2_ERR_CALLBACK_FAILURE is treated as fatal error code. More specifically, it is treated as if NGHTTP2_ERR_CALLBACK_FAILURE is returned. I guess that envoy returns NGHTTP2_ERR_CALLBACK_FAILURE or other error code which is translated into NGHTTP2_ERR_CALLBACK_FAILURE.

build

The following dependencies have been updated:

• ngtcp2
• nghttp3
• BoringSSL

This release fixes build error without libev.

third-party

llhttp has been updated.

Cross-compiling mruby is now supported.

nghttpx

UDP_GRO is enabled for QUIC socket.

The initial QUIC packet number is now randomized.

h2load

UDP_GRO is enabled for QUIC socket.

build

The following dependencies have been updated:

• ngtcp2
• nghttp3
• OpenSSL(quictls)
• BoringSSL
• libbpf

h2load

This release fixes HTTP/3 upload stall bug.

lib

libnghttp2 uses ngtcp2/sfparse to parse Structured Field Values.

build

The following dependencies have been updated:

• ngtcp2
• nghttp3
• OpenSSL(quictls)
• BoringSSL

third-party

Bumped mruby to 3.2.0.

nghttpx

nghttpx now sends NEW_TOKEN on path change.

This release fixes numeric hostname verification in peer certificate.

When quitting, nghttpx now waits for all worker processes to stop. Previously, we just exit the event loop when the last process exits. But the because of the bug, it does not work as intended.

nghttpx logs a correct PID on fork.

nghttpx now waits for new worker process to be ready before sending graceful shutdown event to the existing worker processes to avoid down time during configuration reload.

Fixes the bug that causes 400 response after HTTP upgrade failure.

doc

sphinx_rtd_theme has been removed from the repository and archive.

build

The following dependencies have been updated:

• ngtcp2
• nghttp3
• OpenSSL(quictls)
• BoringSSL
• libbpf

CMake build now checks core and extra components to find libevent.

python

The deprecated Python bindings has been removed.

libnghttp2_asio

The deprecated libnghttp2_asio has been removed.

third-party

llhttp and neverbleed have been updated.

nghttpx

This release fixes the bug that stalls TLS connection.

integration

This release adds more http3 integration tests.