CVE-2019-1000021 is a high-severity (CVSS 7.5) vulnerability in slixmpp. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for slixmpp — see the affected versions and patch details below.
slixmpp Incorrect Access Control
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
slixmppReal-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
slixmpp version before commit 7cd73b594e8122dddf847953fcfc85ab4d316416 contains an incorrect Access Control vulnerability in XEP-0223 plugin (Persistent Storage of Private Data via PubSub) options profile, used for the configuration of default access model that can result in all of the contacts of the victim can see private data having been published to a PEP node. This attack appears to be exploitable if the user of this library publishes any private data on PEP, the node isn't configured to be private. This vulnerability appears to have been fixed in commit 7cd73b594e8122dddf847953fcfc85ab4d316416 which is included in slixmpp 1.4.2.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | slixmpp | all versions | 1.4.2pip install --upgrade 'slixmpp==1.4.2' |
Affected Products
slixmppslixmpp_projectResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for slixmpp, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update slixmpp to 1.4.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-1000021 is resolved across your whole dependency graph.
Workarounds
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
Frequently Asked Questions
Is CVE-2019-1000021 in your dependencies?
Find it across PyPI, including transitive dependencies.