curl and libcurl 8.13.1

 Public curl releases:         267
 Command line options:         268
 curl_easy_setopt() options:   307
 Public functions in libcurl:  96
 Contributors:                 3384

This release includes the following changes:


This release includes the following bugfixes:

 o async-threaded resolver: use ref counter [10]
 o cmake/FindNGTCP2: simplify multi-pkg-config detection [27]
 o cmake: use absolute paths for completion targets [40]
 o configure: fix --disable-rt [20]
 o configure: restore link checks [25]
 o conncache: make Curl_cpool_init return void [15]
 o content_encoding: Transfer-Encoding parser improvements [31]
 o contrithanks.sh: drop set -e [6]
 o curl_krb5: only use functions if FTP is still enabled [21]
 o eventfd: fix feature guards [24]
 o genserv.pl: fail with a message if `openssl` is missing or failing [14]
 o hostip: fix build without threaded-resolver and without DoH [17]
 o hostip: show the correct name on proxy resolve error [37]
 o http2: fix stream window size after unpausing [34]
 o http: fix a build error when all auths are disabled [16]
 o http_aws_sigv4: add additional verbose log statements [39]
 o http_negotiate: fix non-SSL build with GSSAPI [23]
 o https-connect: fix httpsrr target check [36]
 o if2ip: build the function also if FTP is present [19]
 o INSTALL-CMAKE.md: fix typo
 o INSTALL.md: update the minimal libcurl size example
 o lib: add const to clientwriter tables
 o lib: make Curl_easyopts const [44]
 o lib: unify conversions to/from hex [3]
 o libtest/first: stop defining MEMDEBUG_NODEFINES [32]
 o parsedate: provide Curl_wkday also for GnuTLS builds [13]
 o processhelp.pm: avoid potential endless loop, log more (Windows) [5]
 o rand: update comment on Curl_rand_bytes weak random [35]
 o rustls: make max size of cert and key reasonable [41]
 o scripts: completion.pl: sort the completion file for all shells [9]
 o scripts: fix --opts-dir help in completion.pl
 o socket: use accept4 when available [7]
 o test1658: add unit test for the HTTPS RR decoder [28]
 o test: make unittest 1308 into a libtest [4]
 o tests/README.md: document --test-duphandle [8]
 o tests/README.md: list the openssl tool among the prerequisites [12]
 o tests/serverhelp: remove last remnants of http-pipe server [1]
 o tests: fix some test tag mismatches
 o tests: mark ipfs tests to require ipfs [2]
 o tests: move a boolean variable out of the path section
 o tests: prefer `--insecure` over `-k` [43]
 o tests: remove some unused test case sections
 o tests: unify test case keywords
 o tests: use a more portable null device path [38]
 o VERSIONS: list all past releases [22]
 o vtls: fix build with ssl but without http [18]
 o winbuild: add the deprecation warning to the README [29]

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 Support for the msh3 HTTP/3 backend
 o The winbuild build system
 o TLS libraries not supporting TLS 1.3

 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:

  Abhinav Singhal, Andrew Kirillov, Andy Pan, Carlos Henrique Lima Melara,
  Dagobert Michelsen, Dan Fandrich, Daniel Engberg, Daniel Stenberg,
  Jean-Christophe Amiel, Jonathan Rosa, Nigel Brittain, Pavel Kropachev,
  Ray Satiro, renovate[bot], Stefan Eissing, Tomas Volf, Viktor Szakats,
  x1sc0 on github, Yedaya Katsman
  (19 contributors)

References to bug reports and discussions on issues:

 [1] = https://curl.se/bug/?i=16924
 [2] = https://curl.se/bug/?i=16947
 [3] = https://curl.se/bug/?i=16888
 [4] = https://curl.se/bug/?i=16891
 [5] = https://curl.se/bug/?i=16908
 [6] = https://curl.se/bug/?i=16914
 [7] = https://curl.se/bug/?i=16979
 [8] = https://curl.se/bug/?i=16944
 [9] = https://curl.se/bug/?i=16985
 [10] = https://curl.se/bug/?i=16916
 [12] = https://curl.se/bug/?i=16942
 [13] = https://curl.se/bug/?i=16943
 [14] = https://curl.se/bug/?i=16926
 [15] = https://curl.se/bug/?i=16936
 [16] = https://curl.se/bug/?i=16939
 [17] = https://curl.se/bug/?i=16938
 [18] = https://curl.se/bug/?i=16935
 [19] = https://curl.se/bug/?i=16933
 [20] = https://curl.se/bug/?i=16932
 [21] = https://curl.se/bug/?i=16925
 [22] = https://curl.se/bug/?i=16907
 [23] = https://curl.se/bug/?i=16919
 [24] = https://curl.se/mail/lib-2025-04/0000.html
 [25] = https://curl.se/mail/lib-2025-04/0004.html
 [27] = https://curl.se/bug/?i=16980
 [28] = https://curl.se/bug/?i=16972
 [29] = https://curl.se/bug/?i=16957
 [31] = https://curl.se/bug/?i=16956
 [32] = https://curl.se/bug/?i=16978
 [34] = https://curl.se/bug/?i=16955
 [35] = https://curl.se/bug/?i=16965
 [36] = https://curl.se/bug/?i=16966
 [37] = https://curl.se/bug/?i=16958
 [38] = https://curl.se/bug/?i=16929
 [39] = https://curl.se/bug/?i=16952
 [40] = https://curl.se/bug/?i=16946
 [41] = https://curl.se/bug/?i=16951
 [43] = https://curl.se/bug/?i=16878
 [44] = https://curl.se/bug/?i=16950