curl and libcurl 8.21.0

 Public curl releases:         275
 Command line options:         274
 curl_easy_setopt() options:   308
 Public functions in libcurl:  100
 Authors:                      1481
 Contributors:                 3696

This release includes the following changes:

 o curl: named globs in output file name for upload glob references [77]
 o HTTP/3: add proxy CONNECT and MASQUE CONNECT-UDP support (ngtcp2 QUIC) [53]
 o http2: remove stream dependency tracking [40]
 o lib: drop support for CURLAUTH_DIGEST_IE [4]
 o libssh: add support for SHA256 host public keys [57]
 o tool_urlglob: add named globs [92]

This release includes the following bugfixes:

 o asyn-thrdd: fix result processing without wakeup socketpair [2]
 o autotools: mbedtls detection fixes [163]
 o BUFQ.md: re-sync with source code [111]
 o build: omit zlib pkg-config reference for Android [130]
 o cf-h2-prox: fix peer leak [132]
 o cf-h2-proxy: drop interim responses [47]
 o cf-socket: set scope_id for IPv6 link-local addresses [150]
 o cfilters: fix busy loop on blocked transfers [72]
 o CIPHERS.md: fix the example that uses only TLS 1.3 [137]
 o cmake: auto-select static nghttp2/nghttp3/ngtcp2 Config [8]
 o cmake: export/forward `NGTCP2_CRYPTO_BACKEND` [99]
 o cmake: fix three issues generating lib options in config files [126]
 o cmake: fix zstd CMake config name [5]
 o cmake: opt in `MSVC_VERSION` 1951 to picky warnings [55]
 o cmake: quote `COMPONENTS` string in `curl-config.in.cmake` [80]
 o connect: remove deref of freed pointer in trace call [128]
 o content_encoding: fix limit failure message [171]
 o content_encoding: timeout during slow decoding [170]
 o cookie: compare path case sensitively [52]
 o cookie: simplify strstore(), remove outdated comment [12]
 o cookie: trim trailing dots when checking PSL [39]
 o creds: add sasl service name [75]
 o creds: mask OAuth bearer token in trace logs [117]
 o creds: remove two unused functions [158]
 o curl_easy_pause.md: rephrase the stream cache when pause clause [120]
 o curl_easy_setopt.md: change options when no transfer runs [122]
 o curl_ntlm_core: fix nettle 4+ builds in certain MultiSSL combos [87]
 o curl_ntlm_core: propagate DES `CryptEncrypt()` error [84]
 o curl_sha512_256: fix result code on error [166]
 o CURLOPT_ECH.md: simplify the description language [18]
 o CURLOPT_HAPROXYPROTOCOL.md: only sent for newly setup connections [32]
 o CURLOPT_MAXFILESIZE: clarify this also works for on-going transfers [78]
 o CURLOPT_SHARE: warn about early remove [51]
 o CURLOPT_SSH_HOSTKEYFUNCTION.md: for new connections only [48]
 o delta: harden external command invocations [98]
 o dnscache: remove Curl_dns_entry_link [160]
 o docs/libcurl: fix the version for curl_multi_socket_action
 o docs: end "...can be used several times..." sentences with period [34]
 o docs: fix --follow doc typo [97]
 o docs: fix a couple of typos [62]
 o docs: fix grammar and wording in FAQ [66]
 o docs: fix odd wording in CONTRIBUTE.md [107]
 o docs: note CURLOPT_PINNEDPUBLICKEY has no effect on legacy LDAP backend [65]
 o ECH: cleanups [20]
 o event: fix wakeup consumption [93]
 o ftp: avoid accessing EPSV response one byte past the NULL [9]
 o ftp: remove 2 Curl_resolv_blocking() calls [30]
 o ftp: remove bits.ftp_use_control_ssl [28]
 o gnutls: allow building with nettle 4.0 [96]
 o gnutls: fix more nettle 4+ compatibility issues [94]
 o GnuTLS: require 3.7.2 for earlydata [103]
 o gsasl: fix potential double free [56]
 o gtls: fix ignored return and uninitialized status in OCSP check [49]
 o gtls: fix some typos [15]
 o gtls: use the correct return code in trace output [173]
 o h3-proxy: fix callback return values, and a typo in tests [139]
 o hostip: remove unused MAX_HOSTCACHE_LEN and MAX_DNS_CACHE_SIZE [101]
 o http: don't pass on set cookies to new origins [140]
 o idn: replace header guards with forward declaration [100]
 o KNOWN_BUGS.md: remove fixed GnuTLS <-> OpenSSL incompat bug [41]
 o KNOWN_BUGS: remove stale Threads::Threads entry [135]
 o ldap: fix minor leak on write callback error [24]
 o ldap: fix to not leak `attribute` on OOM (WinLDAP) [79]
 o ldap: switch off chasing referrals [114]
 o lib678: fix to not be perma-skipped [10]
 o lib: make `__STDC_VERSION__` literals `L` (where missing)
 o lib: two minor typos [16]
 o libcurl-easy.md: minor clarifications [19]
 o libssh: map SSH_KNOWN_HOSTS_OTHER to CURLKHMATCH_MISMATCH [125]
 o m4: drop redundant conditions in TLS library detections [155]
 o managen: apply minor fixes and improvements [115]
 o mbedtls: null-terminate the private key blob [36]
 o mk-unity.pl: `#include`, and not concatenate input headers [124]
 o mqtt: validate PINGRESP and DISCONNECT have remaining_length == 0 [7]
 o multi: handle pause in multi socket callback [109]
 o multi: silence gcc 16 `-Wnull-dereference`, bump CI job to test [54]
 o netrc: scanner refactor [121]
 o ngtcp2: fail handshake directly [138]
 o pytest: re-enable test test_05_01 and test_05_02 for quiche 0.29.0+ [154]
 o pythonlint.sh: make it fail on error, fix ruff warnings in pytest [67]
 o rtsp: bump buf after rtsp_filter_rtp() [88]
 o runner.pm: apply minor correctness fix [105]
 o runner.pm: set `CURL_TESTNUM` for `precheck` commands [13]
 o rustls: error on CURLOPT_CRLFILE with native CA store [59]
 o schannel: check `schannel_sha256sum()` success, and more [165]
 o schannel: enforce Extended Key Usage for custom CA roots [29]
 o schannel: error on TLS 1.3-only with cipher list [136]
 o schannel: fix revoke_best_effort setting for proxy [70]
 o schannel_verify: avoid out of blob access [11]
 o scripts: catch Credits-to contributors [127]
 o setopt: changing the proxy port is also a proxy change [23]
 o setopt: clear proxy auth properly on NULL [81]
 o setopt: fix to honor `CURLOPT_PROXY_CAINFO_BLOB` over Native CA [26]
 o setopt: gate a few proxy TLS options by checking backend support [35]
 o setopt: more careful cleanup of the HSTS cache [45]
 o show-headers.md: mention bold headers and --no-styled-output [17]
 o spnego_sspi: honor CURLOPT_GSSAPI_DELEGATION for Windows SSPI [89]
 o spnego_sspi: preserve distinction btw policy-only and uncond delegation [74]
 o src: fix comment typos [83]
 o SSLCERTS: document 8.19.0 default Native CA builds (Windows) [14]
 o sspi: clear SSPI credentials on AcquireCredentialsHandle failure [76]
 o test1588: use %TESTNUMBER, not hard-coded number [118]
 o test1981: explicitly set the locale [85]
 o tests: add an assert to avoid IPC blocking [69]
 o tests: fix unit1636 with --disable-progress-meter [37]
 o tftp: avoid the timeout calc if the timeout is crazy [151]
 o tftp: stricter option name checks [90]
 o tidy-up: add space around operators, where missing [147]
 o tidy-up: apply clang-format fixes [153]
 o tidy-up: miscellaneous [106]
 o tls: fix incomplete mTLS config in conn reuse and session cache [108]
 o tool: add a retry delay for transfers to same origin on 429 [61]
 o tool_formparse.c: fix two minor comment typos [25]
 o tool_formparse: polish error message + make two functions static [1]
 o tool_formparse: tool2curlparts is no longer recursive [33]
 o tool_urlglob: avoid overflow at end of range [22]
 o tool_urlglob: better 'Duplicate glob name' position [82]
 o tool_urlglob: make globbing error reported for correct position [91]
 o transfer: clear referer when set to NULL [112]
 o unix-sockets: ignore proxy settings [6]
 o url: compare full origin when setting credentials [42]
 o url: connection reuse fixes for starttls [68]
 o url: detect proxy changes read from environment [110]
 o url: fix connection reuse for starttls protocols [27]
 o url: keep the question mark for empty queries [73]
 o url: remove ssh_config_matches [31]
 o url: remove superfluous check [131]
 o url: url_match_destination fix [43]
 o urlapi: accept 0X prefix in IPv4 address as well [63]
 o urlapi: change more lowercase percent-encoded to uppercase [71]
 o urlapi: compare zone-id in Curl_url_same_origin() [95]
 o urlapi: consume trailing dots after IPv4 numerical addresses [50]
 o urlapi: deny hostnames with more than one trailing dot [58]
 o urlapi: drop base fragment on empty redirect [64]
 o urlapi: fix an issue parsing file URLs [149]
 o urlapi: fix redirect handling if CURLU_NO_GUESS_SCHEME is set [46]
 o urlapi: forbid '|' in host [172]
 o urlapi: handle redirect without set scheme with default-scheme [38]
 o user-agent.md: mention double quotes too [3]
 o vtls: more large buffer support and error checks for SHA-256 [164]
 o vtls: use Curl_safecmp for CRLfile and pinned_key comparison [116]
 o vtls_scache: include signature_algorithms in the SSL peer cache key [123]
 o vtls_spack: drop redundant macro fallbacks [167]
 o VULN-DISCLOSURE-POLICY.md: emphasize the no email thank you part [113]
 o VULN-DISCLOSURE-POLICY.md: test code is not secure [119]
 o websockets: auto-tunnel through http proxy [102]
 o windows: update MS SDK versions in comments [60]
 o x509asn1: fix DH public key parameter extraction [44]
 o x509asn1: fix operator order in do_pubkey [21]

This release includes the following known bugs:

 See https://curl.se/docs/knownbugs.html

For all changes ever done in curl:

 See https://curl.se/changes.html

Planned upcoming removals include:

 o local crypto implementations
 o NTLM
 o SMB
 o TLS-SRP support

 See https://curl.se/dev/deprecate.html

This release would not have looked like this without help, code, reports and
advice from friends like these:

  0xN3R3K3, 11soda11, Alan De Smet, ambikeesshh, amitbidlan, Andrei Rybak,
  Andrew Nesbitt, Aritra Basu, azraelxuemo on hackerone, Bartel Sielski,
  Bastian Jesuiter, Bill Mill, chrizilla on github, co-authors in libssh2,
  Dan Fandrich, Daniel Gustafsson, Daniel Stenberg, Dario Vinella,
  dependabot[bot], Earnestly on github, Elise Vance, Emanuel Krollmann,
  Fabian Keil, Harry Sintonen, htasta, jeffhuang, Jeremy Nicoll,
  Johannes Schlatow, Joshua Rogers, Kai Pastor, Mark Esler, Max Dymond, mik,
  Mike-menny on github, mulan_dh on hackerone, parasol-aser, penpal,
  Peter Krefting, Raymond Steen, Ray Satiro, renovate[bot], Ross Burton,
  Sergio Correia, sfan5 on github, Shintomon Mathew, Sollace on github,
  Song X. Gao, Stefan Eissing, Tim Martin, tiymat, Viktor Szakats,
  Will Cosgrove, Xi Ruoyao, x-xiang on github
  (54 contributors)

References to bug reports and discussions on issues:

 [1] = https://curl.se/bug/?i=21510
 [2] = https://curl.se/bug/?i=21476
 [3] = https://curl.se/mail/archive-2026-04/0029.html
 [4] = https://curl.se/bug/?i=21486
 [5] = https://curl.se/bug/?i=21538
 [6] = https://curl.se/bug/?i=21630
 [7] = https://hackerone.com/reports/3702718
 [8] = https://curl.se/bug/?i=21470
 [9] = https://curl.se/bug/?i=21545
 [10] = https://curl.se/bug/?i=21641
 [11] = https://curl.se/bug/?i=21543
 [12] = https://curl.se/bug/?i=21541
 [13] = https://curl.se/bug/?i=21640
 [14] = https://curl.se/bug/?i=21634
 [15] = https://curl.se/bug/?i=21498
 [16] = https://curl.se/bug/?i=21496
 [17] = https://curl.se/bug/?i=21495
 [18] = https://curl.se/bug/?i=21536
 [19] = https://curl.se/bug/?i=21491
 [20] = https://curl.se/bug/?i=21532
 [21] = https://curl.se/bug/?i=21533
 [22] = https://curl.se/bug/?i=21529
 [23] = https://curl.se/bug/?i=21485
 [24] = https://curl.se/bug/?i=21530
 [25] = https://curl.se/bug/?i=21480
 [26] = https://curl.se/bug/?i=21631
 [27] = https://curl.se/bug/?i=21522
 [28] = https://curl.se/bug/?i=21521
 [29] = https://curl.se/bug/?i=21629
 [30] = https://curl.se/bug/?i=21512
 [31] = https://curl.se/bug/?i=21519
 [32] = https://curl.se/bug/?i=21517
 [33] = https://curl.se/bug/?i=21518
 [34] = https://curl.se/bug/?i=21644
 [35] = https://curl.se/bug/?i=21514
 [36] = https://curl.se/bug/?i=21515
 [37] = https://curl.se/bug/?i=21500
 [38] = https://curl.se/bug/?i=21632
 [39] = https://curl.se/bug/?i=21636
 [40] = https://curl.se/bug/?i=21723
 [41] = https://curl.se/bug/?i=21720
 [42] = https://curl.se/bug/?i=21575
 [43] = https://curl.se/bug/?i=21573
 [44] = https://curl.se/bug/?i=21595
 [45] = https://curl.se/bug/?i=21615
 [46] = https://curl.se/bug/?i=21721
 [47] = https://curl.se/bug/?i=21626
 [48] = https://curl.se/bug/?i=21606
 [49] = https://curl.se/bug/?i=21679
 [50] = https://curl.se/bug/?i=21635
 [51] = https://curl.se/bug/?i=21633
 [52] = https://curl.se/bug/?i=21616
 [53] = https://curl.se/bug/?i=21153
 [54] = https://curl.se/bug/?i=21707
 [55] = https://curl.se/bug/?i=21714
 [56] = https://curl.se/bug/?i=21609
 [57] = https://curl.se/bug/?i=21605
 [58] = https://curl.se/bug/?i=21622
 [59] = https://curl.se/bug/?i=21614
 [60] = https://curl.se/bug/?i=21621
 [61] = https://curl.se/bug/?i=21355
 [62] = https://curl.se/bug/?i=21617
 [63] = https://curl.se/bug/?i=21820
 [64] = https://curl.se/bug/?i=21745
 [65] = https://curl.se/bug/?i=21682
 [66] = https://curl.se/bug/?i=21593
 [67] = https://curl.se/bug/?i=21597
 [68] = https://curl.se/bug/?i=21665
 [69] = https://curl.se/bug/?i=21688
 [70] = https://curl.se/bug/?i=21683
 [71] = https://curl.se/bug/?i=21592
 [72] = https://curl.se/bug/?i=21671
 [73] = https://curl.se/bug/?i=21544
 [74] = https://curl.se/bug/?i=21583
 [75] = https://curl.se/bug/?i=21585
 [76] = https://curl.se/bug/?i=21642
 [77] = https://curl.se/bug/?i=21407
 [78] = https://curl.se/bug/?i=21582
 [79] = https://curl.se/bug/?i=21576
 [80] = https://curl.se/bug/?i=21699
 [81] = https://curl.se/bug/?i=21696
 [82] = https://curl.se/bug/?i=21567
 [83] = https://curl.se/bug/?i=21570
 [84] = https://curl.se/bug/?i=21569
 [85] = https://curl.se/bug/?i=21749
 [87] = https://curl.se/bug/?i=21562
 [88] = https://curl.se/bug/?i=21563
 [89] = https://curl.se/bug/?i=21528
 [90] = https://curl.se/bug/?i=21560
 [91] = https://curl.se/bug/?i=21561
 [92] = https://curl.se/bug/?i=21409
 [93] = https://curl.se/bug/?i=21547
 [94] = https://curl.se/bug/?i=21557
 [95] = https://curl.se/bug/?i=21686
 [96] = https://curl.se/bug/?i=21169
 [97] = https://curl.se/bug/?i=21553
 [98] = https://curl.se/bug/?i=21104
 [99] = https://curl.se/bug/?i=21523
 [100] = https://curl.se/bug/?i=21551
 [101] = https://curl.se/bug/?i=21550
 [102] = https://curl.se/bug/?i=21663
 [103] = https://curl.se/bug/?i=21750
 [105] = https://curl.se/bug/?i=21672
 [106] = https://curl.se/bug/?i=21646
 [107] = https://curl.se/bug/?i=21705
 [108] = https://curl.se/bug/?i=21667
 [109] = https://curl.se/bug/?i=21748
 [110] = https://curl.se/bug/?i=21666
 [111] = https://curl.se/bug/?i=21678
 [112] = https://curl.se/bug/?i=21741
 [113] = https://curl.se/bug/?i=21747
 [114] = https://curl.se/bug/?i=21732
 [115] = https://curl.se/bug/?i=21670
 [116] = https://curl.se/bug/?i=21668
 [117] = https://curl.se/bug/?i=21659
 [118] = https://curl.se/bug/?i=21662
 [119] = https://curl.se/bug/?i=21660
 [120] = https://curl.se/bug/?i=21658
 [121] = https://curl.se/bug/?i=21624
 [122] = https://curl.se/bug/?i=21604
 [123] = https://curl.se/bug/?i=21651
 [124] = https://curl.se/bug/?i=21656
 [125] = https://curl.se/bug/?i=21724
 [126] = https://curl.se/bug/?i=21654
 [127] = https://curl.se/bug/?i=21653
 [128] = https://curl.se/bug/?i=21649
 [130] = https://curl.se/bug/?i=21647
 [131] = https://curl.se/bug/?i=21650
 [132] = https://curl.se/bug/?i=21602
 [135] = https://curl.se/bug/?i=21734
 [136] = https://curl.se/bug/?i=21702
 [137] = https://curl.se/bug/?i=21719
 [138] = https://curl.se/bug/?i=21712
 [139] = https://curl.se/bug/?i=21802
 [140] = https://curl.se/bug/?i=21794
 [147] = https://curl.se/bug/?i=21793
 [149] = https://curl.se/bug/?i=21743
 [150] = https://curl.se/bug/?i=21669
 [151] = https://curl.se/bug/?i=21782
 [153] = https://curl.se/bug/?i=21786
 [154] = https://curl.se/bug/?i=21784
 [155] = https://curl.se/bug/?i=21781
 [158] = https://curl.se/bug/?i=21776
 [160] = https://curl.se/bug/?i=21774
 [163] = https://curl.se/bug/?i=21727
 [164] = https://curl.se/bug/?i=21771
 [165] = https://curl.se/bug/?i=21739
 [166] = https://curl.se/bug/?i=21767
 [167] = https://curl.se/bug/?i=21768
 [170] = https://curl.se/bug/?i=21603
 [171] = https://curl.se/bug/?i=21756
 [172] = https://curl.se/bug/?i=21762
 [173] = https://curl.se/bug/?i=21766
