Low privilege condition filter escapes Twig sandbox, recovers "securityKey" and reaches RCE

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Craft CMS allows any authenticated control panel user to submit an element-search condition whose element selector is evaluated as a sandboxed Twig object template. Craft’s allowed column filter delegates property lookup to Yii ArrayHelper, outside Twig’s SecurityPolicy. Repeated single-segment lookups therefore bypass the sandbox’s empty property/method allowlists. The vulnerable condition value is ultimately cast to an integer. That does not protect the secret: the template can return author ID 1 when a guessed key character is correct and an impossible ID otherwise. The JSON endpoint returns entries for the first case and an empty array for the second, forming a stable remote character oracle. After recovering GeneralConfig::securityKey, the same user can compute Craft’s generic HMAC wire format offline. Signed parameters such as redirect are then accepted and passed to unsandboxed View::renderObjectTemplate(), where Twig’s string-callable form can invoke native PHP callables. The regression proof uses the harmless substr() callback and observes abcdef becoming cdef; it does not execute an OS command.

Source published

23 Oct 2026 21:58:51 UTC

Source modified

23 Oct 2026 21:58:51 UTC

Observed here

23 Oct 2026 22:48:20 UTC

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CVSS 4.0 · 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS 3.1 · 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H