diff --git a/crates/fuzzing/src/generators/module.rs b/crates/fuzzing/src/generators/module.rs
index 765ed2e11f95..98f05b2c2476 100644
--- a/crates/fuzzing/src/generators/module.rs
+++ b/crates/fuzzing/src/generators/module.rs
@@ -56,6 +56,12 @@ impl<'a> Arbitrary<'a> for ModuleConfig {
         // do that most of the time.
         config.disallow_traps = u.ratio(9, 10)?;
 
+        // FIXME(#9523) this `if` should ideally be deleted, requires some
+        // refactoring internally.
+        if config.custom_page_sizes_enabled && config.threads_enabled {
+            config.custom_page_sizes_enabled = false;
+        }
+
         Ok(ModuleConfig { config })
     }
 }
diff --git a/docs/stability-wasm-proposals.md b/docs/stability-wasm-proposals.md
index 5e6d192a742b..54484e5b9c2b 100644
--- a/docs/stability-wasm-proposals.md
+++ b/docs/stability-wasm-proposals.md
@@ -46,7 +46,7 @@ column is below.
 | [`function-references`]  | ✅      | ✅    | ❌       | ❌     | ✅  | ❌    |
 | [`gc`] [^6]              | ✅      | ✅    | ❌[^7]   | ❌     | ✅  | ❌    |
 | [`wide-arithmetic`]      | ❌      | ✅    | ✅       | ✅     | ✅  | ✅    |
-| [`custom-page-sizes`]    | ❌      | ✅    | ✅       | ✅     | ✅  | ❌    |
+| [`custom-page-sizes`]    | ❌      | ✅    | ⚠️[^8]    | ✅     | ✅  | ❌    |
 
 [^6]: There is also a [tracking
     issue](https://github.com/bytecodealliance/wasmtime/issues/5032) for the
@@ -54,6 +54,8 @@ column is below.
 [^7]: The implementation of GC has [known performance
     issues](https://github.com/bytecodealliance/wasmtime/issues/9351) which can
     affect non-GC code when the GC proposal is enabled.
+[^8]: Using custom-page-sizes is [known to have issues when combined with shared
+    memories](https://github.com/bytecodealliance/wasmtime/issues/9523).
 
 ## Unimplemented proposals