Fatal error: pll__() exhausts memory with 4295229440 bytes allocation

Hi,

We’ve hit a critical bug where pll__() causes a PHP fatal error that takes the

entire site down. The allocation size (4295229440 bytes = exactly 2^32)
strongly
suggests an integer overflow inside pll__() or its internal string processing.

Environment:

• WordPress: 6.9.1
• Polylang: 3.7.7 (also tested 3.7.8 — issue not fixed)
• WooCommerce: 10.5.2
• Flexible Checkout Fields: 4.1.35
• PHP: 8.3 Error:
  PHP Fatal error: Allowed memory size of 268435456 bytes exhausted
  (tried to allocate 4295229440 bytes) in
  wp-content/plugins/flexible-checkout-fields/inc/wpdesk-woo27-functions.php on
  line 79 The call stack leads to:
  wpdesk__( $text, $domain ) → pll__( $text ) → fatal error Key observations:

1. The allocation size 4295229440 = 0x100000000 = 2^32 is characteristic of a
   signed/unsigned integer overflow (e.g., -1 interpreted as unsigned 32-bit)
2. The error fires on EVERY page request once triggered — the site becomes
   completely inaccessible
3. The bug did NOT occur immediately after plugin installation. It appeared
   6 days later, triggered by wp-cron rebuilding Polylang’s translation cache
4. Polylang 3.7.8 changelog does not address this issue Likely cause:
   pll__() appears to pass a specific string to an internal function that
   performs
   a size calculation resulting in integer overflow, then attempts to allocate
   the
   resulting ~4GB of memory. Workaround:
   Disabling Flexible Checkout Fields immediately resolves the issue, suggesting
   the problematic string originates from that plugin’s translation strings. Request:
   Could you investigate what happens inside pll__() when it receives a string
   that
   triggers this overflow? Adding input validation or a memory_get_usage() guard
   before large allocations might prevent site-wide crashes even if the root
   cause
   is in a third-party plugin’s string. This is version 3.7.7 regression — the combination with WooCommerce plugins
   worked fine with earlier Polylang versions on the same site. Thank you.