---
id: CVE-2017-9047
title: A buffer overflow was discovered in libxml2 20904-GITv2.9.4-16-g0741801
summary: >-
  A buffer overflow was discovered in libxml2 20904-GITv2.9.4-16-g0741801. The
  function xmlSnprintfElementContent in valid.c is supposed to recursively dump
  the element content definition into a char buffer 'buf' of size 'size'. The
  variab…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-119
vendor: xmlsoft
product: libxml2
affected:
  - libxml2 = 2.9.4
published: '2017-05-18'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T07:16:40.757'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2017-9047'
references:
  - url: 'http://www.debian.org/security/2017/dsa-3952'
    label: cve@mitre.org
  - url: 'http://www.openwall.com/lists/oss-security/2017/05/15/1'
    label: cve@mitre.org
  - url: 'http://www.securityfocus.com/bid/98599'
    label: cve@mitre.org
  - url: >-
      https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
    label: cve@mitre.org
  - url: >-
      https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
    label: cve@mitre.org
  - url: 'https://security.gentoo.org/glsa/201711-01'
    label: cve@mitre.org
  - url: 'http://www.debian.org/security/2017/dsa-3952'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'http://www.openwall.com/lists/oss-security/2017/05/15/1'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'http://www.securityfocus.com/bid/98599'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.gentoo.org/glsa/201711-01'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
epss: 0.03185
epssPercentile: 0.87766
ingestedAt: '2026-10-14T07:21:04.795Z'
---

## Overview

A buffer overflow was discovered in libxml2 20904-GITv2.9.4-16-g0741801. The function xmlSnprintfElementContent in valid.c is supposed to recursively dump the element content definition into a char buffer 'buf' of size 'size'. The variable len is assigned strlen(buf). If the content->type is XML_ELEMENT_CONTENT_ELEMENT, then (i) the content->prefix is appended to buf (if it actually fits) whereupon (ii) content->name is written to the buffer. However, the check for whether the content->name actually fits also uses 'len' rather than the updated buffer length strlen(buf). This allows us to write about "size" many bytes beyond the allocated memory. This vulnerability causes programs that use libxml2, such as PHP, to crash.

## Affected

- `libxml2 = 2.9.4`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.