5.3 Medium
CVSS3
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N
0.001 Low
EPSS
Percentile
21.9%
Oppia is an online learning platform. When comparing a received CSRF token against the expected token, Oppia uses the string equality operator (==
), which is not safe against timing attacks. By repeatedly submitting invalid tokens, an attacker can brute-force the expected CSRF token character by character. Once they have recovered the token, they can then submit a forged request on behalf of a logged-in user and execute privileged actions on that user’s behalf. In particular the function to validate received CSRF tokens is at oppia.core.controllers.base.CsrfTokenManager.is_csrf_token_valid
. An attacker who can lure a logged-in Oppia user to a malicious website can perform any change on Oppia that the user is authorized to do, including changing profile information; creating, deleting, and changing explorations; etc. Note that the attacker cannot change a user’s login credentials. An attack would need to complete within 1 second because every second, the time used in computing the token changes. This issue has been addressed in commit b89bf80837
which has been included in release 3.3.2-hotfix-2
. Users are advised to upgrade. There are no known workarounds for this vulnerability.
[
{
"vendor": "oppia",
"product": "oppia",
"versions": [
{
"version": ">= 1.1.0, < 3.3.2-hotfix-2",
"status": "affected"
}
]
}
]