PHP version 8.4.21 (07 May 2026)

Core:

• Fixed bug GH-19983 (GC assertion failure with fibers, generators and destructors). (iliaal)
• Fixed bug GH-21478 (Forward property operations to real instance for initialized lazy proxies). (iliaal)
• Fixed bug GH-21605 (Missing addref for Countable::count()). (ilutov)
• Fixed bug GH-21699 (Assertion failure in shutdown_executor when resolving self::/parent::/static:: callables if the error handler throws). (macoaure)
• Fixed bug GH-21603 (Missing addref for __unset). (ilutov)
• Fixed bug GH-21760 (Trait with class constant name conflict against enum case causes SEGV). (Pratik Bhujel)

CLI:

• Fixed bug GH-21754 (--rf command line option with a method triggers ext/reflection deprecation warnings). (DanielEScherzer)

Curl:

• Add support for brotli and zstd on Windows. (Shivam Mathur)

DOM:

• Fixed GHSA-4jhr-8w89-j733 and GH-21566 (Dom\XMLDocument::C14N() emits duplicate xmlns declarations after setAttributeNS()). (CVE-2026-7263) (David Carlier)
• Fixed bug GH-21688 (segmentation fault on empty HTMLDocument). (David Carlier)
• Upgrade to lexbor v2.7.0. (CVE-2026-29078, CVE-2026-29079) (ndossche, ilutov)

FPM:

• Fixed GHSA-7qg2-v9fj-4mwv (XSS within status endpoint). (CVE-2026-6735) (Jakub Zelenka)

Iconv:

• Fixed bug GH-17399 (iconv memory leak on bailout). (iliaal)

MBString:

• Fixed GHSA-wm6j-2649-pv75 (Null pointer dereference in php_mb_check_encoding() via mb_ereg_search_init()). (CVE-2026-7259) (vi3tL0u1s)
• Fixed GHSA-74r9-qxhc-fx53 (Out-of-bounds access in mbfl_name2encoding_ex()). (CVE-2026-6104) (ilutov)

Opcache:

• Fixed bug GH-21158 (JIT: Assertion jit->ra[var].flags & (1<<0) failed in zend_jit_use_reg). (Arnaud)
• Fixed bug GH-21593 (Borked function JIT JMPNZ smart branch). (ilutov)
• Fixed bug GH-21460 (COND optimization regression). (Dmitry, Arnaud)
• Fixed faulty returns out of zend_try block in zend_jit_trace(). (ilutov)

OpenSSL:

• Fix a bunch of memory leaks and crashes on edge cases. (ndossche)

PDO_Firebird:

• Fixed GHSA-w476-322c-wpvm (SQL injection via NUL bytes in quoted strings). (CVE-2025-14179) (SakiTakamachi)

Phar:

• Restore is_link handler in phar_intercept_functions_shutdown. (iliaal)
• Fixed bug GH-21797 (phar: NULL dereference in Phar::webPhar() when SCRIPT_NAME is absent from SAPI environment). (iliaal)
• Fix memory leak in Phar::offsetGet(). (iliaal)
• Fix memory leak in phar_add_file(). (iliaal)
• Fixed bug GH-21799 (phar: propagate phar_stream_flush return value from phar_stream_close). (iliaal)
• Fix memory leak in phar_verify_signature() when md_ctx is invalid. (JarneClauw)

Random:

• Fixed bug GH-21731 (Random\Engine\Xoshiro256StarStar::__unserialize() accepts all-zero state). (iliaal)

Session:

• Fixed memory leak when session GC callback return a refcounted value. (jorgsowa)

SOAP:

• Fixed GHSA-85c2-q967-79q5 (Stale SOAP_GLOBAL(ref_map) pointer with Apache Map). (CVE-2026-6722) (ilutov)
• Fixed GHSA-m33r-qmcv-p97q (Use-after-free after header parsing failure with SOAP_PERSISTENCE_SESSION). (CVE-2026-7261) (ilutov)
• Fixed GHSA-hmxp-6pc4-f3vv (Broken Apache map value NULL check). (CVE-2026-7262) (ilutov)

SPL:

• Fixed bug GH-21499 (RecursiveArrayIterator getChildren UAF after parent free). (Girgias)
• Fix concurrent iteration and deletion issues in SplObjectStorage. (ndossche)

Standard:

• Fixed GHSA-96wq-48vp-hh57 (Signed integer overflow of char array offset). (CVE-2026-7568) (TimWolla)
• Fixed GHSA-m8rr-4c36-8gq4 (Consistently pass unsigned char to ctype.h functions). (CVE-2026-7258) (ilutov)

Streams:

• Fixed bug GH-21468 (Segfault in file_get_contents w/ a https URL and a proxy set). (ndossche)

XSL:

• Fixed bug GH-21600 (Segfault on module shutdown). (David Carlier)