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.

Published: 2017-08-24 Last update: 2026-05-13 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2017-11424 is rated Moderate Risk (44/100): CVSS High severity, with low exploitation likelihood (EPSS 0.19%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2017-11424

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-26 0.53% 0.19% -0.33%
2 2026-04-21 0.85% 0.53% -0.32%
3 2026-04-16 — 0.85% —

Full EPSS history (9 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2017-11424

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.0 HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:P/A:N Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2017-11424

GitHub Security Advisory for CVE-2017-11424

GHSA-r9jw-mwhq-wp62 · Severity: high · Ecosystem: pip — PyJWT vulnerable to key confusion attacks

OS Trackers for CVE-2017-11424

vendor priority summary link
debian not yet assigned CVE-2017-11424 not yet assigned priority: Debian including 1 source packages (pyjwt), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2017-11424
redhat medium — https://access.redhat.com/security/cve/CVE-2017-11424
ubuntu medium CVE-2017-11424 medium priority: Ubuntu including 1 source packages (pyjwt), 4 status rows across 4 suites (trusty, upstream, xenial, zesty): released 2, DNE 1, needed 1. https://ubuntu.com/security/CVE-2017-11424

Affected software / configurations for CVE-2017-11424

Vendor Product Version Raw CPE
pyjwt_project pyjwt <= 1.5.0 cpe:2.3:a:pyjwt_project:pyjwt:*:*:*:*:*:*:*:*
debian debian_linux 8.0 cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

References for CVE-2017-11424

URL Tags
http://www.debian.org/security/2017/dsa-3979 Third Party Advisory
https://github.com/jpadilla/pyjwt/pull/277 Issue Tracking Patch Third Party Advisory
cvelogic Threat Intelligence