CVE-2017-11424
PyJWT vulnerable to key confusion attacks
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
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.
- Record
CVE-2017-11424- CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - CVSS 2.0
- 5.0 Medium
AV:N/AC:L/Au:N/C:N/I:P/A:N - Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2017-11424- Updated
- 2026-11-02
EUVDEUVD-2017-0103 No score
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.
- Record
EUVD-2017-0103- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-r9jw-mwhq-wp62
PyJWT vulnerable to key confusion attacks
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.
- Record
GHSA-r9jw-mwhq-wp62- CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
OSV
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.
- Record
CVE-2017-11424- CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
OSVDEBIAN-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.
- Record
DEBIAN-CVE-2017-11424- CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
Show 4 moreShow less
OSVGHSA-r9jw-mwhq-wp62
PyJWT vulnerable to key confusion attacks
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.
- Record
GHSA-r9jw-mwhq-wp62- CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
OSVUBUNTU-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.
- Record
UBUNTU-CVE-2017-11424- CVSS 3.0
- 7.5 High
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - Updated
- 2026-11-02
OSVPYSEC-2017-24 No score
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.
- Record
PYSEC-2017-24- Updated
- 2026-11-02
OSVUSN-3407-1 No score
pyjwt vulnerability
It was discovered that a vulnerability in PyJWT doesn't check invalid_strings properly for some public keys. A remote attacker could take advantage of a key confusion to craft JWTs from scratch.
- Record
USN-3407-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
pyjwtPyPI |
before 1.5.1 | 1.5.1 |
pyjwtDebian:12 |
before 1.4.2-1.1 | 1.4.2-1.1 |
pyjwtDebian:13 |
before 1.4.2-1.1 | 1.4.2-1.1 |
pyjwtDebian:14 |
before 1.4.2-1.1 | 1.4.2-1.1 |
pyjwtDebian:8 |
before 0.2.1-1+deb8u2, plus listed versions 0.2.1-10.2.1-1+deb8u1 |
0.2.1-1+deb8u2 |
pyjwtDebian:9 |
before 1.4.2-1+deb9u1, plus listed versions 1.4.2-1 |
1.4.2-1+deb9u1 |
pyjwtPyPI |
before 1.5.1, plus listed versions 0.1.10.1.20.1.30.1.40.1.5 Show 22 moreShow less0.1.60.1.70.1.80.1.90.2.00.2.10.2.30.3.00.3.10.3.20.4.00.4.10.4.20.4.31.0.01.0.11.1.01.3.01.4.01.4.11.4.21.5.0 |
1.5.1 |
pyjwtUbuntu:16.04:LTS |
before 1.3.0-1ubuntu0.1, plus listed versions 1.0.0-0ubuntu11.3.0-1 |
1.3.0-1ubuntu0.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2017-11424 is a high vulnerability (CVSS 7.5) in Pyjwt Project Pyjwt, published August 24, 2017. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.80%, the 78th percentile. Fixed in pyjwt 1.5.1.