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Vulnerabilities

Vulnerability · CVE-2021-3517

There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11.

Published May 19, 2021 · catalog updated Oct 14, 2026 · There is a flaw

Check this week

CVE-2021-3517 is not in CISA KEV. FIRST estimates a 16.99% chance of exploitation in the next 30 days. Check whether you run There is a flaw.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (There is a flaw).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.6
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
16.99%
Remediation
Advisory link
Affected products
cpe debian/debian linux · cpe fedoraproject/fedora · cpe netapp/active iq unified manager · cpe netapp/hci h410c firmware · cpe oracle/communications cloud native core network function cloud native environment · cpe redhat/enterprise linux

There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11. An attacker who is able to supply a crafted file to be processed by an application linked with the affected functionality of libxml2 could trigger an out-of-bounds read. The most likely impact of this flaw is to application availability, with some potential impact to confidentiality and integrity if an attacker is able to use memory information to further exploit the application.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe debian/debian linux9.0
  • cpe fedoraproject/fedora33
  • cpe fedoraproject/fedora34
  • cpe netapp/active iq unified managerversion unspecified
  • cpe netapp/hci h410c firmwareversion unspecified
  • cpe oracle/communications cloud native core network function cloud native environment1.10.0
  • cpe redhat/enterprise linux8.0
  • cpe redhat/jboss core servicesversion unspecified
  • cpe xmlsoft/libxml2version unspecified

How to fix CVE-2021-3517

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2021-3517 is not in CISA KEV. FIRST estimates a 16.99% chance of exploitation in the next 30 days. Check whether you run There is a flaw.

Which versions are affected?

Compare what you have installed with debian/debian linux 9.0; oracle/communications cloud native core network function cloud native environment 1.10.0; redhat/enterprise linux 8.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-125: Out-of-bounds Read; CWE-787: Out-of-bounds Write. EPSS 16.99%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. May 19, 2021 · NIST NVD

    Detected

    There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11. An attacker who is able to supply a crafted file to be processed by an application linked with the affected functionality of libxml2 could trigger an out-of-bounds read. The most likely impact of this flaw is to application availability, with some potential impact to confidentiality and integrity if an a

  2. Oct 14, 2026 · NIST NVD

    Updated

    There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11. An attacker who is able to supply a crafted file to be processed by an application linked with the affected functionality of libxml2 could trigger an out-of-bounds read. The most likely impact of this flaw is to application availability, with some potential impact to confidentiality and integrity if an a

Sources

  • CVE.orgVulnerability recordCVE-2021-3517

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2021-3517

    30-day exploitation probability 17.0%

    first.org
  • NIST NVDVulnerability recordCVE-2021-3517

    There is a flaw in the xml entity encoding functionality of libxml2 in versions before 2.9.11. An attacker who is able to supply a crafted file to be processed by an application linked with the affected functionality of libxml2 could trigger an out-of-bounds read. The most likely

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 16, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.