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KafkaApplication · Apache

CVE-2025-27817

HIGH · 7.5 CVSS v3.1 Published 2025-06-10
Fix available
A fix is available. Upgrade to 3.9.1 or later.
See remediation →
84/100
Remediation priority · High
High EPSS Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A possible arbitrary file read and SSRF vulnerability has been identified in Apache Kafka Client. Apache Kafka Clients accept configuration data for setting the SASL/OAUTHBEARER connection with the brokers, including "sasl.oauthbearer.token.endpoint.url" and "sasl.oauthbearer.jwks.endpoint.url". Apache Kafka allows clients to read an arbitrary file and return the content in the error log, or sending requests to an unintended location. In applications where Apache Kafka Clients configurations can be specified by an untrusted party, attackers may use the "sasl.oauthbearer.token.endpoint.url" and "sasl.oauthbearer.jwks.endpoint.url" configuratin to read arbitrary contents of the disk and environment variables or make requests to an unintended location. In particular, this flaw may be used in Apache Kafka Connect to escalate from REST API access to filesystem/environment/URL access, which may be undesirable in certain environments, including SaaS products. Since Apache Kafka 3.9.1/4.0.0, we have added a system property ("-Dorg.apache.kafka.sasl.oauthbearer.allowed.urls") to set the allowed urls in SASL JAAS configuration. In 3.9.1, it accepts all urls by default for backward compatibility. However in 4.0.0 and newer, the default value is empty list and users have to set the allowed urls explicitly.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Apache Kafka Client accepts SASL/OAUTHBEARER configuration parameters (sasl.oauthbearer.token.endpoint.url and sasl.oauthbearer.jwks.endpoint.url) that allow untrusted users to specify arbitrary file paths (reading disk contents and environment variables) or arbitrary URLs (enabling SSRF). This is exploitable in environments where Kafka client configurations can be controlled by untrusted parties, particularly Apache Kafka Connect REST API users.

MitigationUpgrade to Apache Kafka 3.9.1 or 4.0.0+ and configure the -Dorg.apache.kafka.sasl.oauthbearer.allowed.urls system property to whitelist permitted URLs, blocking file:// and untrusted HTTP endpoints.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
KafkaApplication
Affected:>= 3.1.0, < 3.9.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Kafka version
    Run 'kafka-topics.sh --version' or check the kafka-core_2.x.jar manifest, or inspect the classpath for kafka-version.properties
    Affected if Version is 3.1.0 or higher but lower than 3.9.1
  2. Locate client configuration files
    Search for .properties or .yml files containing Kafka client configurations, typically in conf/ or config/ directories, or environment variables passed to Kafka Connect workers
    Affected if Files exist with Kafka consumer or producer settings
  3. Identify SASL/OAUTHBEARER configuration
    Grep for 'sasl.mechanism=OAUTHBEARER' in client property files or search for 'sasl.oauthbearer' in configurations
    Affected if OAUTHBEARER mechanism is enabled
  4. Inspect oauthbearer endpoint URL values
    Search for 'sasl.oauthbearer.token.endpoint.url' and 'sasl.oauthbearer.jwks.endpoint.url' properties and examine their values
    Affected if Values contain file:// paths, untrusted HTTP/HTTPS URLs, or wildcard/arbitrary endpoints not restricted to trusted identity providers
  5. Check Kafka Connect REST API exposure
    Review whether Kafka Connect REST API is network-accessible to untrusted users or accepts connector configurations from untrusted sources
    Affected if Kafka Connect REST API is exposed without strict access controls and OAUTHBEARER is configured

You are affected if running Kafka 3.1.0 through 3.9.0 with SASL/OAUTHBEARER enabled and the endpoint URLs are set to arbitrary file paths or untrusted HTTP URLs that could be controlled by untrusted parties.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 3.9.1 or later
Fixed in 3.9.1
Interim mitigation

Upgrade to Apache Kafka 3.9.1 or 4.0.0+ and configure the -Dorg.apache.kafka.sasl.oauthbearer.allowed.urls system property to whitelist permitted URLs, blocking file:// and untrusted HTTP endpoints.

Recommended fix High confidence

3.9.1 or 4.0.0 (4.0.0+ recommended for stricter default security)

  1. 1. Upgrade Apache Kafka to version 3.9.1 or 4.0.0 or later to resolve the SSRF vulnerability.
  2. 2. For Kafka 4.0.0 and later: Add the system property '-Dorg.apache.kafka.sasl.oauthbearer.allowed.urls' to your startup scripts, specifying a comma-separated list of allowed OAuth token endpoint URLs and JWKS endpoint URLs that clients are permitted to access.
  3. 3. For Kafka Connect or any application accepting untrusted Kafka client configurations: Ensure that 'sasl.oauthbearer.token.endpoint.url' and 'sasl.oauthbearer.jwks.endpoint.url' can only be set by trusted administrators, not by end users via the REST API.
  4. 4. After upgrading, verify that Kafka clients and connectors function correctly with the new OAuth/OAUTHBEARER configuration.
Caveat In Kafka 4.0.0+, the default for sasl.oauthbearer.allowed.urls is an empty list, requiring explicit configuration of allowed URLs - existing deployments relying on default behavior will need to add this system property.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Kafka Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

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