CVE-2021-44878
The "none" algorithm does not require any signature verification when validating the ID tokens, which allows the attacker to bypass the token validation by injecting a malformed ID token using "none" as the value of "alg" key in the header with an empty…
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.90%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
If an OpenID Connect provider supports the "none" algorithm (i.e., tokens with no signature), pac4j v5.3.0 (and prior) does not refuse it without an explicit configuration on its side or for the "idtoken" response type which is not secure and violates the OpenID Core Specification. The "none" algorithm does not require any signature verification when validating the ID tokens, which allows the attacker to bypass the token validation by injecting a malformed ID token using "none" as the value of "alg" key in the header with an empty signature value.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- EPSS
- 0.90% probability · 58th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-347
- Affected
- pac4j/pac4j
- Source
- cve@mitre.org
References
- https://github.com/pac4j/pac4j/commit/22b82ffd702a132d9f09da60362fc6264fc281aePatch, Third Party Advisory
- https://openid.net/specs/openid-connect-core-1_0.html#IDTokenProduct, Third Party Advisory
- https://www.pac4j.org/blog/cve_2021_44878_is_this_serious.htmlMitigation, Vendor Advisory
- https://github.com/pac4j/pac4j/commit/22b82ffd702a132d9f09da60362fc6264fc281aePatch, Third Party Advisory
- https://openid.net/specs/openid-connect-core-1_0.html#IDTokenProduct, Third Party Advisory
- https://www.pac4j.org/blog/cve_2021_44878_is_this_serious.htmlMitigation, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.