How severe is CVE-2021-38153?

CVE-2021-38153 has a CVSS score of 5.9/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-38153?

CVE-2021-38153 affects the following packages: org.apache.kafka:kafka_2.11 (Maven), org.apache.kafka:kafka_2.12 (Maven), org.apache.kafka:kafka_2.12 (Maven), org.apache.kafka:kafka_2.12 (Maven), org.apache.kafka:kafka_2.13 (Maven), org.apache.kafka:kafka_2.13 (Maven), org.apache.kafka:kafka_2.13 (Maven), org.apache.kafka:kafka-clients (Maven), and 2 more. Ecosystems affected: Maven.

How do I fix CVE-2021-38153?

No patched version of org.apache.kafka:kafka_2.11 has shipped for CVE-2021-38153 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

How do I detect CVE-2021-38153 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.kafka:kafka_2.11. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2021-38153 if there is no patch (or I can't update yet)?

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 does O3 Security protect against CVE-2021-38153?

O3 pinpoints whether CVE-2021-38153 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2021-38153 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-38153 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-38153?

CVE-2021-38153 has an EPSS (Exploit Prediction Scoring System) score of 5.8%, placing it in the 92th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was CVE-2021-38153 published, and has it been updated?

CVE-2021-38153 was published on September 22, 2021 and was last updated on April 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven

CVE-2021-38153

MEDIUM

Observable Discrepancy in Apache Kafka

Also known asBIT-kafka-2021-38153GHSA-3j6g-hxx5-3q26

Published

Sep 22, 2021

Updated

Apr 10, 2026

Affected

10 pkgs

Patched

9 / 10

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

5.8%probability of exploitation in next 30 days

Lower Risk92th percentile+4.21%

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.

Blast Radius

10 pkgs affected

☕org.apache.kafka:kafka_2.11☕org.apache.kafka:kafka_2.12☕org.apache.kafka:kafka_2.12☕org.apache.kafka:kafka_2.12☕org.apache.kafka:kafka_2.13☕org.apache.kafka:kafka_2.13☕org.apache.kafka:kafka_2.13☕org.apache.kafka:kafka-clients+2 more

Real-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

Some components in Apache Kafka use Arrays.equals to validate a password or key, which is vulnerable to timing attacks that make brute force attacks for such credentials more likely to be successful. Users should upgrade to 2.8.1 or higher, or 3.0.0 or higher where this vulnerability has been fixed. The affected versions include Apache Kafka 2.0.0, 2.0.1, 2.1.0, 2.1.1, 2.2.0, 2.2.1, 2.2.2, 2.3.0, 2.3.1, 2.4.0, 2.4.1, 2.5.0, 2.5.1, 2.6.0, 2.6.1, 2.6.2, 2.7.0, 2.7.1, and 2.8.0.

Affected Packages

10 total 9 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.apache.kafka:kafka_2.11`	≥ 2.0.0	No fix
☕Maven	`org.apache.kafka:kafka_2.12`	≥ 2.0.0&&< 2.6.3	2.6.3
☕Maven	`org.apache.kafka:kafka_2.12`	≥ 2.7.0&&< 2.7.2	2.7.2
☕Maven	`org.apache.kafka:kafka_2.12`	≥ 2.8.0&&< 2.8.1	2.8.1
☕Maven	`org.apache.kafka:kafka_2.13`	≥ 2.4.0&&< 2.6.3	2.6.3
☕Maven	`org.apache.kafka:kafka_2.13`	≥ 2.7.0&&< 2.7.2	2.7.2

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.kafka:kafka_2.11. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
No patched version of org.apache.kafka:kafka_2.11 has shipped for CVE-2021-38153 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
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 pinpoints whether CVE-2021-38153 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2021-38153. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Some components in Apache Kafka use `Arrays.equals` to validate a password or key, which is vulnerable to timing attacks that make brute force attacks for such credentials more likely to be successful. Users should upgrade to 2.8.1 or higher, or 3.0.0 or higher where this vulnerability has been fixed. The affected versions include Apache Kafka 2.0.0, 2.0.1, 2.1.0, 2.1.1, 2.2.0, 2.2.1, 2.2.2, 2.3.0, 2.3.1, 2.4.0, 2.4.1, 2.5.0, 2.5.1, 2.6.0, 2.6.1, 2.6.2, 2.7.0, 2.7.1, and 2.8.0.

O3 Security · Impact-Aware SCA

Is CVE-2021-38153 in your dependencies?

O3 detects CVE-2021-38153 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works