CVE-2026-9537
Mojo::JWT versions before 1.02 for Perl verify HMAC signatures with a non-constant-time string comparison
Description
Mojo::JWT versions before 1.02 for Perl verify HMAC signatures with a non-constant-time string comparison. The decode() method compares the supplied signature to the recomputed HMAC with Perl's eq operator, which stops at the first differing byte, so the comparison time varies with the number of matching leading bytes. A caller that decodes attacker supplied tokens leaks the expected signature through this timing variation, which can be aggregated over many requests to recover the signature and forge a token.
INFO
Published Date :
July 17, 2026, 4:17 p.m.
Last Modified :
July 17, 2026, 4:17 p.m.
Remotely Exploit :
No
Source :
9b29abf9-4ab0-4765-b253-1875cd9b441e
Affected Products
The following products are affected by CVE-2026-9537
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
Solution
- Update Mojo::JWT to version 1.02 or later.
- Ensure JWT verification uses constant-time comparison.
- Avoid using attacker-supplied tokens for decoding.
- Validate token integrity using secure methods.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-9537.
| URL | Resource |
|---|---|
| https://github.com/jberger/Mojo-JWT/commit/b8aefb846613e44b5b12bc170898ffd5b05094a2.patch |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-9537 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-9537
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-9537 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-9537 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 9b29abf9-4ab0-4765-b253-1875cd9b441e
Jul. 17, 2026
Action Type Old Value New Value Added Affected [{'repo': 'http://github.com/jberger/Mojo-JWT', 'vendor': 'JBERGER', 'product': 'Mojo::JWT', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '1.02', 'versionType': 'custom'}], 'packageName': 'Mojo-JWT', 'programFiles': ['lib/Mojo/JWT.pm'], 'collectionURL': 'https://cpan.org/modules', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'Mojo::JWT::decode'}]}] Added Description Mojo::JWT versions before 1.02 for Perl verify HMAC signatures with a non-constant-time string comparison. The decode() method compares the supplied signature to the recomputed HMAC with Perl's eq operator, which stops at the first differing byte, so the comparison time varies with the number of matching leading bytes. A caller that decodes attacker supplied tokens leaks the expected signature through this timing variation, which can be aggregated over many requests to recover the signature and forge a token. Added CWE CWE-208 Added Reference https://github.com/jberger/Mojo-JWT/commit/b8aefb846613e44b5b12bc170898ffd5b05094a2.patch