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Vulnerabilities

Vulnerability · CVE-2018-20843

In libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources whil

Published Jun 24, 2019 · catalog updated Oct 15, 2026 · libexpat project

Check if you run it

No confirmed exploitation is on record for CVE-2018-20843. EPSS is 7.11%. Act only if a listed version of libexpat project is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
7.11%
Remediation
Advisory link
Affected products
Debian:12 expat · Debian:12 libxmltok · Debian:13 expat · Debian:14 expat · cpe canonical/ubuntu linux · cpe debian/debian linux

In libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources while processing (enough to be usable for denial-of-service attacks).

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.

  • Debian:12 expat0 → 2.2.6-2
  • Debian:12 libxmltok1.2-4, 1.2-4.1, 1.2-4.1~exp1
  • Debian:13 expat0 → 2.2.6-2
  • Debian:14 expat0 → 2.2.6-2
  • cpe canonical/ubuntu linux12.04
  • cpe canonical/ubuntu linux14.04
  • cpe canonical/ubuntu linux16.04
  • cpe canonical/ubuntu linux18.04
  • cpe canonical/ubuntu linux18.10
  • cpe canonical/ubuntu linux19.04
  • cpe debian/debian linux8.0
  • cpe fedoraproject/fedora29
  • cpe libexpat project/libexpatversion unspecified
  • cpe opensuse/leap15.0
  • cpe oracle/hospitality res 3700version unspecified
  • cpe tenable/nessusversion unspecified

How to fix CVE-2018-20843

What to do

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

Should you patch?

No confirmed exploitation is on record for CVE-2018-20843. EPSS is 7.11%. Act only if a listed version of libexpat project is installed.

Which versions are affected?

Compare what you have installed with canonical/ubuntu linux 12.04; canonical/ubuntu linux 14.04; canonical/ubuntu linux 16.04; canonical/ubuntu linux 18.04. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-611: XML External Entity (XXE). EPSS 7.11%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Debian security

Code

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

Timeline

Detection, updates, and resolution for this record.

  1. Jun 24, 2019 · NIST NVD

    Detected

    In libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources while processing (enough to be usable for denial-of-service attacks).

  2. Oct 14, 2026 · NIST NVD

    Updated

    In libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources while processing (enough to be usable for denial-of-service attacks).

  3. Oct 14, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    expat fixed in 2.2.6-2; expat fixed in 2.2.6-2; expat fixed in 2.2.6-2

  4. Oct 14, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    expat fixed in 2.2.6-2

  5. Oct 14, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    In libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources while processing (enough to be usable for denial-of-service attacks).

  6. Oct 15, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    In libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources while processing (enough to be usable for denial-of-service attacks).

  7. Oct 15, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    In libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources while processing (enough to be usable for denial-of-service attacks).

Sources

  • CVE.orgVulnerability recordCVE-2018-20843

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2018-20843

    30-day exploitation probability 7.1%

    first.org
  • NIST NVDVulnerability recordCVE-2018-20843

    In libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources while processing (enough to be usable for denial-of-service attacks).

    nvd.nist.gov
  • OpenSSF OSV / OSV ScannerPackage advisoryDEBIAN-CVE-2018-20843
    osv.dev

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.