CVE-2021-41571 is a medium-severity (CVSS 6.5) CWE-863 vulnerability in org.apache.pulsar:pulsar. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for org.apache.pulsar:pulsar — see the affected versions and patch details below.
Improper Input Validation in Apache Pulsar
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
org.apache.pulsar:pulsar☕org.apache.pulsar:pulsar☕org.apache.pulsar:pulsarReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
In Apache Pulsar it is possible to access data from BookKeeper that does not belong to the topics accessible by the authenticated user. The Admin API get-message-by-id requires the user to input a topic and a ledger id. The ledger id is a pointer to the data, and it is supposed to be a valid it for the topic. Authorisation controls are performed against the topic name and there is not proper validation the that ledger id is valid in the context of such ledger. So it may happen that the user is able to read from a ledger that contains data owned by another tenant. This issue affects Apache Pulsar Apache Pulsar version 2.8.0 and prior versions; Apache Pulsar version 2.7.3 and prior versions; Apache Pulsar version 2.6.4 and prior versions.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.pulsar:pulsar | all versions | No fix |
| ☕Maven | org.apache.pulsar:pulsar | ≥ 2.7.0&&< 2.7.4 | 2.7.4org.apache.pulsar:pulsar:2.7.4 |
| ☕Maven | org.apache.pulsar:pulsar | ≥ 2.8.0&&< 2.8.1 | 2.8.1org.apache.pulsar:pulsar:2.8.1 |
Affected Products
pulsarapacheResearch 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 org.apache.pulsar:pulsar, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
A fix is available for CVE-2021-41571; check the affected-versions list above or the advisory for the patched release of org.apache.pulsar:pulsar, then make sure no transitive dependency still pins the vulnerable range.
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-2021-41571 in your dependencies?
Find it across Maven, including transitive dependencies.