Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2018-20843

CVE-2018-20843HIGH

n/a n/a — 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 …

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   N  U  N  N  H    7.5   .0711   94.2     —

AFFECTED
  Product  Versions  Fixed
  n/a      n/a –     —

TIMELINE
  Jun 24  Reserved by mitre
  Jun 24  Published (CNA: mitre)
  Oct 14  EXPLOIT PUBLISHED — CVE-2018-20843. Public exploit reference added.

CWE-611 · CNA: mitre · CVSS v3.1 · 22 references · NVD status: Modified

Description

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).

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
June 24, 2019	Reserved	Reserved by mitre
June 24, 2019	Published	Published (CNA: mitre)
October 14, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2018-20843. Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
n/a	n/a	—	n/a	—

Weaknesses

CWE-611

References (22)

http://lists.opensuse.org/opensuse-security-announce/2019-07/msg00039.html [Mailing List, Third Party Advisory]
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5226 [Issue Tracking, Third Party Advisory]
https://cert-portal.siemens.com/productcert/html/ssa-398330.html
https://github.com/libexpat/libexpat/blob/R_2_2_7/expat/Changes [Release Notes, Third Party Advisory]
https://github.com/libexpat/libexpat/issues/186 [Issue Tracking, Patch, Third Party Advisory]
https://github.com/libexpat/libexpat/pull/262 [Exploit, Patch, Third Party Advisory]
https://github.com/libexpat/libexpat/pull/262/commits/11f8838bf99ea0a6f0b76f9760c43704d00c4ff6 [Patch, Third Party Advisory]
https://lists.debian.org/debian-lts-announce/2019/06/msg00028.html [Mailing List, Third Party Advisory]
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CEJJSQSG3KSUQY4FPVHZ7ZTT7FORMFVD/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IDAUGEB3TUP6NEKJDBUBZX7N5OAUOOOK/
https://seclists.org/bugtraq/2019/Jun/39 [Mailing List, Third Party Advisory]
https://security.gentoo.org/glsa/201911-08 [Third Party Advisory]
https://security.netapp.com/advisory/ntap-20190703-0001/ [Third Party Advisory]
https://support.f5.com/csp/article/K51011533 [Third Party Advisory]
https://usn.ubuntu.com/4040-1/ [Third Party Advisory]
https://usn.ubuntu.com/4040-2/ [Third Party Advisory]
https://www.debian.org/security/2019/dsa-4472 [Third Party Advisory]
https://www.oracle.com/security-alerts/cpuApr2021.html [Patch, Third Party Advisory]
https://www.oracle.com/security-alerts/cpuapr2020.html [Patch, Third Party Advisory]
https://www.oracle.com/security-alerts/cpuoct2020.html [Patch, Third Party Advisory]
https://www.oracle.com/security-alerts/cpuoct2021.html [Patch, Third Party Advisory]
https://www.tenable.com/security/tns-2021-11 [Third Party Advisory]

Authoritative record: CVE-2018-20843 at cve.org

Weaknesses: CWE-611

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2018-20843 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Monday, October 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.