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GHSA-35wc-cvqg-78fp

LowCVSS 2.7 / 10
Published May 21, 2026·Last modified May 21, 2026
Affected Components(0)

No affected components available

Description

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.

Risk Scores
Base Score
2.7

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence
2.7

Limited exploitation activity has been observed. Close monitoring and planned remediation are recommended.

EPSS
0.30%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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