CVE-2023-6681 is a medium-severity (CVSS 5.3) Uncontrolled Resource Consumption vulnerability in jwcrypto. A fix is available for jwcrypto — see the affected versions and patch details below.
Jwcrypto: denail of service via specifically crafted jwe
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-6681.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-6681 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
jwcryptoReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Impact
Denial of Service, Applications that allow the use of the PBKDF2 algorithm.
Patches
A patch is available that sets the maximum number of default rounds.
Workarounds
Applications that do not need to use PBKDF2 should simply specify the algorithms use and exclude it from the list. Applications that need to use the algorithm should upgrade to the new version that allows to set a maximum rounds number.
Acknowledgement
The issues was reported by Jingcheng Yang and Jianjun Chen from Sichuan University and Zhongguancun Lab
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | jwcrypto | all versions | 1.5.1pip install --upgrade 'jwcrypto==1.5.1' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jwcrypto, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update jwcrypto to 1.5.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-6681 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-6681 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-6681. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
The identified vulnerability within the jwcrypto package, presents a moderate severity concern rather than a important one due to several mitigating factors. While the unbounded PBES2 Count value in PBKDF2 algorithms can potentially facilitate a Denial of Service (DoS) attack, its severity is tempered by the fact that…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 8 | idm:client-8100020240417004735.143e9e98 | RHSA-2024:3267 |
| Red Hat Enterprise Linux 9 | python-jwcrypto-0:1.5.6-2.el9 | RHSA-2024:9281 |
Frequently Asked Questions
Is CVE-2023-6681 in your dependencies?
O3 Security finds CVE-2023-6681 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.