GHSA-whqr-fgm5-x77q OpenStack Keystone's federated token rescoping mechanism doesn't propagate the original token's expiry to the newly issued token

• PyPI keystone: >= 14.0.0, < 27.0.2 → fixed in 27.0.2 • PyPI keystone: >= 28.0.0, < 28.0.2 → fixed in 28.0.2 • PyPI keystone: >= 29.0.0, < 29.0.2 → fixed in 29.0.2

An issue was discovered in OpenStack Keystone before 29.0.2. The Keystone federated token rescoping mechanism does not propagate the original token's expiry to the newly issued token. When a federated user rescopes a token via POST /v3/auth/tokens, the handle_scoped_token() function in the mapped authentication plugin returns response data without an expires_at value. The token provider falls back to issuing a token with a fresh default TTL. By rescoping repeatedly before each token expires, a user can maintain access indefinitely, bypassing operator-configured token lifetime policies. This is a variant of CVE-2012-3426. Only deployments using federated identity (SAML2, OpenID Connect) are affected.