Vulnerability CVE-2017-11424


Published: 2017-08-24

Description:
In PyJWT 1.5.0 and below the `invalid_strings` check in `HMACAlgorithm.prepare_key` does not account for all PEM encoded public keys. Specifically, the PKCS1 PEM encoded format would be allowed because it is prefaced with the string `-----BEGIN RSA PUBLIC KEY-----` which is not accounted for. This enables symmetric/asymmetric key confusion attacks against users using the PKCS1 PEM encoded public keys, which would allow an attacker to craft JWTs from scratch.

Type:

CWE-noinfo

CVSS2 => (AV:N/AC:L/Au:N/C:N/I:P/A:N)

CVSS Base Score
Impact Subscore
Exploitability Subscore
5/10
2.9/10
10/10
Exploit range
Attack complexity
Authentication
Remote
Low
No required
Confidentiality impact
Integrity impact
Availability impact
None
Partial
None
Affected software
Pyjwt project -> Pyjwt 
Debian -> Debian linux 

 References:
http://www.debian.org/security/2017/dsa-3979
https://github.com/jpadilla/pyjwt/pull/277

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