GHSA-35wc-cvqg-78fp

ghsaUSosv

twig/intl-extra: Unbounded formatter memoisation in keyed on template-controlled arguments

view advisory published 2026-05-21Licence: CC-BY-4.0

### Description `IntlExtension` memoises every `\IntlDateFormatter` and `\NumberFormatter` it creates in instance-level arrays keyed on a hash that includes `locale`, `pattern`, `attrs` and other values that are ordinary named arguments of the `format_datetime` / `format_date` / `format_time` / `format_number` / `format_currency` filters. There is no size limit and no eviction. A template that iterates over many distinct `pattern` (or `locale`, or `grouping_used`, ...) values therefore allocates one ICU formatter object per distinct value and pins it for the entire lifetime of the `Twig\Environment`. Because ICU allocates its backing buffers outside the Zend memory manager, this growth is not bounded by `memory_limit`. On long-running runtimes (RoadRunner, Swoole, FrankenPHP worker mode, ReactPHP) where the `Environment` outlives a single request, the cache also accumulates across requests. ### Resolution The formatter caches are now bounded in size (100 entries each) and evict on a FIFO basis. ### Credits Twig would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and providing the fix.

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describes (1)

Related CVEs.

IDseverity exploitable
CVE-2026-46629USmedium6.5—
Twig is a template language for PHP. Prior to 3.26.0, twig/intl-extra memoises IntlDateFormatter and NumberFormatter instances in arrays keyed by template-controlled filter argumen…
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