diff --git a/CHANGELOG.md b/CHANGELOG.md
index 019d8b61..dffa8f5c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,16 @@
 ## OpenBLAS v0.3.34 (v0.3.34)
 
+### 0.3.34.678.0 (2026-11-04)
+
+- update to OpenBLAS develop 02f58544, which includes OpenMathLib/OpenBLAS#6105.
+  This fixes a crash in the default allocator's overflow area: overflow slots
+  re-mapped a new buffer on every allocation and eventually wrote past the end
+  of `new_release_info`. Seen on Windows ARM64 with many concurrent callers.
+  It also includes OpenMathLib/OpenBLAS#6220, which exports `xerbla_` again
+  (hidden since the switch to `-fvisibility=hidden`).
+- raise `NUM_THREADS` from 24 to 64 on Windows (amd64 and arm64), matching
+  the Linux and macOS builds.
+
 ### 0.3.34.481.3 (2026-11-2)
 
 - Refactor gha upload to anaconda.org
diff --git a/OpenBLAS b/OpenBLAS
index 5137bb62..02f58544 160000
--- a/OpenBLAS
+++ b/OpenBLAS
@@ -1 +1 @@
-Subproject commit 5137bb62b4ca24fa88873809b845ffc18e601256
+Subproject commit 02f585444a0fba2505cfda77cc6684de008ea477
diff --git a/openblas_commit.txt b/openblas_commit.txt
index c5fd8e91..5730c1ac 100644
--- a/openblas_commit.txt
+++ b/openblas_commit.txt
@@ -1 +1 @@
-v0.3.34-481-g5137bb62
+v0.3.34-678-g02f58544
diff --git a/pyproject.toml b/pyproject.toml
index f03f77a9..5f368444 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -8,8 +8,8 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "scipy-openblas64"
-# 0.3.34-481-g5137bb62
-version = "0.3.34.481.3"
+# v0.3.34-678-g02f58544
+version = "0.3.34.678.0"
 requires-python = ">=3.7"
 description = "Provides OpenBLAS for python packaging"
 readme = "README.md"
diff --git a/tools/build_steps_win_arm64.bat b/tools/build_steps_win_arm64.bat
index 6446b3ca..36890381 100755
--- a/tools/build_steps_win_arm64.bat
+++ b/tools/build_steps_win_arm64.bat
@@ -174,7 +174,7 @@ cmake .. -G Ninja ^
  -DSYMBOLPREFIX="scipy_" ^
  -DLIBNAMEPREFIX="scipy_" ^
  -DUSE_THREADS=1 ^
- -DNUM_THREADS=24 ^
+ -DNUM_THREADS=64 ^
  %interface_flags%
 
 if errorlevel 1 exit /b 1
diff --git a/tools/build_steps_windows.sh b/tools/build_steps_windows.sh
index 0674e3c8..0ef916d6 100644
--- a/tools/build_steps_windows.sh
+++ b/tools/build_steps_windows.sh
@@ -117,7 +117,7 @@ sed -e "s/^VERSION = .*/VERSION = ${version}/" -i.bak Makefile.rule
 # Build OpenBLAS
 CFLAGS="$CFLAGS -fvisibility=protected -fno-ident" \
 make BINARY=$build_bits DYNAMIC_ARCH=1 USE_THREAD=1 USE_OPENMP=0 \
-     NUM_THREADS=24 NO_WARMUP=1 NO_AFFINITY=1 CONSISTENT_FPCSR=1 \
+     NUM_THREADS=64 NO_WARMUP=1 NO_AFFINITY=1 CONSISTENT_FPCSR=1 \
      BUILD_LAPACK_DEPRECATED=1 TARGET=PRESCOTT BUFFERSIZE=20 \
      LDFLAGS="$LDFLAGS" \
      DYNAMIC_LIST="$dynamic_list" \