Vulnerability Details : CVE-2017-11424
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.
Products affected by CVE-2017-11424
- cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
- cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
- cpe:2.3:a:pyjwt_project:pyjwt:*:*:*:*:*:*:*:*
Exploit prediction scoring system (EPSS) score for CVE-2017-11424
0.08%
Probability of exploitation activity in the next 30 days
EPSS Score History
~ 34 %
Percentile, the proportion of vulnerabilities that are scored at or less
CVSS scores for CVE-2017-11424
Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source | First Seen |
---|---|---|---|---|---|---|
5.0
|
MEDIUM | AV:N/AC:L/Au:N/C:N/I:P/A:N |
10.0
|
2.9
|
NIST | |
7.5
|
HIGH | CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N |
3.9
|
3.6
|
NIST |
References for CVE-2017-11424
-
http://www.debian.org/security/2017/dsa-3979
Debian -- Security Information -- DSA-3979-1 pyjwtThird Party Advisory
-
https://github.com/jpadilla/pyjwt/pull/277
Guard against PKCS1 PEM-encoded public keys by jpadilla · Pull Request #277 · jpadilla/pyjwt · GitHubIssue Tracking;Patch;Third Party Advisory
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