CVE-2026-27205

MEDIUM4.3EPSS 0.01%

Flask session does not add `Vary: Cookie` header when accessed in some ways

發布日:2026/2/19修改日:2026/2/23
也稱為:GHSA-68rp-wp8r-4726CGA-49q7-f9qg-cvhg

描述

When the `session` object is accessed, Flask should set the `Vary: Cookie` header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python `in` operator were overlooked. The severity depends on the application's use of the session, and the cache's behavior regarding cookies. The risk depends on all these conditions being met. 1. The application must be hosted behind a caching proxy that does not ignore responses with cookies. 2. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached. 3. The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.

受影響套件(2)

CVSS 分數

來源版本嚴重程度向量
osvCVSS 4.0—CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
osvCVSS 3.1MEDIUM4.3CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N

參考連結(6)