React Router: Arbitrary Constructor Injection via deserializeErrors() in React Router SSR Hydration

If application code allows attacker supplied input to overwrite certain aspects of errors caught by the SSR process, then it was possible for attacker to trigger unexpected constructor execution on the client which would trigger outbound network traffic. This is only possible with very specific (and unlikely) application layer code. > [!NOTE] > This does not impact your application if you are using Declarative Mode. This only impacts Framework Mode and Data Mode applications doing manual SSR/hydration

Source published

23 Jul 2026 19:34:14 UTC

Source modified

10 Sep 2026 03:50:51 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Publisher rating · MODERATE