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MEDIUM severity

CVE-2021-38153 — kafka_2.11

MEDIUM

CVE-2021-38153 is a medium-severity (CVSS 5.9) CWE-203 vulnerability in org.apache.kafka:kafka_2.11. A fix is available for org.apache.kafka:kafka_2.11 — see the affected versions and patch details below.

Observable Discrepancy in Apache Kafka

Also known asBIT-kafka-2021-38153GHSA-3j6g-hxx5-3q26
Published
Sep 22, 2021
Updated
Aug 7, 2026
Affected
10 pkgs
Patched
9 / 10
Exploits
None indexed
Exploitation data as of Sep 24, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
6.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs93th percentile — riskier than 93% of all scored CVEsHighest risk

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-2021-38153 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 378,567 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

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
EcosystemPackageVulnerable rangeFix
☕Mavenorg.apache.kafka:kafka_2.11≥ 2.0.0No fix
☕Mavenorg.apache.kafka:kafka_2.12≥ 2.0.0&&< 2.6.32.6.3org.apache.kafka:kafka_2.12:2.6.3
☕Mavenorg.apache.kafka:kafka_2.12≥ 2.7.0&&< 2.7.22.7.2org.apache.kafka:kafka_2.12:2.7.2
☕Mavenorg.apache.kafka:kafka_2.12≥ 2.8.0&&< 2.8.12.8.1org.apache.kafka:kafka_2.12:2.8.1
☕Mavenorg.apache.kafka:kafka_2.13≥ 2.4.0&&< 2.6.32.6.3org.apache.kafka:kafka_2.13:2.6.3
☕Mavenorg.apache.kafka:kafka_2.13≥ 2.7.0&&< 2.7.22.7.2org.apache.kafka:kafka_2.13:2.7.2

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.kafka:kafka_2.11, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. 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.

  3. 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.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2021-38153 can be triaged on real exposure rather than presence alone.

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.

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.

Red HatModerate
ProductFixed inAdvisory
Red Hat AMQ Streams 1.6.6see advisoryRHSA-2022:0219
Red Hat AMQ Streams 2.0.0kafkaRHSA-2022:0138
Red Hat build of Quarkus 2.2.5kafka-clientsRHSA-2022:0589
Red Hat Data Grid 8.3.1kafka-clientsRHSA-2022:2232
Red Hat Fuse 7.11kafka-clientsRHSA-2022:5532
RHAF Camel-K 1.8kafka-clientsRHSA-2022:6407
RHINT Camel-Q 2.7see advisoryRHSA-2022:5606
RHINT Service Registry 2.0.3 GAkafka-clientsRHSA-2022:0501

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 Security finds CVE-2021-38153 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works
CVE-2021-38153: kafka_2.11 (Medium 5.9) | O3 Security