Gradio before version 6.15.0 contains a cookie injection vulnerability that allows remote attackers to perform cross-Space session fixation by exploiting a shared module-level HTTP client used across all users in the reverse proxy endpoint. Attackers controlling any HF Space can return a parent-domain cookie that the shared client stores and automatically replays into all subsequent proxy requests to other legitimate Spaces, affecting all users of the same Gradio deployment.
https://www.vulncheck.com/advisories/gradio-cookie-injection-via-shared-pro
https://github.com/gradio-app/gradio/releases/tag/gradio%406.15.0
https://github.com/gradio-app/gradio/pull/13384
https://github.com/gradio-app/gradio/issues/13369
https://github.com/gradio-app/gradio/commit/feb7237d01f359d2ad4ee42d00344e61692b3b39
Published: 2026-05-27
Updated: 2026-05-27
Base Score: 7.1
Vector: CVSS2#AV:N/AC:H/Au:N/C:C/I:C/A:N
Severity: High
Base Score: 6.8
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
Severity: Medium
Base Score: 7.6
Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Severity: High