Security readout for executives and security teams
CVE-2018-20843 is a denial-of-service flaw in Expat before 2.2.7. Specially crafted XML names with many colons can make the parser spend excessive CPU and memory. Systems that parse untrusted XML may become slow or unavailable, but the sources do not indicate data theft or code execution. Exposure is most likely where operating systems, applications, or appliances include vulnerable Expat/libexpat and parse XML from users, network clients, feeds, or APIs. The bundle does not provide a complete affected-product inventory, so dependency and vendor-package checks are required. Treat this as a high-priority availability risk for services that parse untrusted XML. It is less urgent than code execution flaws, but externally reachable XML processing can turn this into an outage issue. Prioritize internet-facing and business-critical systems first. Mitigation focus: Upgrade Expat/libexpat to 2.2.7 or a vendor-fixed backport.; Apply relevant Ubuntu, Debian, Fedora, openSUSE, Gentoo, Oracle, or appliance vendor updates.; Inventory applications and products that bundle Expat rather than relying on system packages..
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
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ATT&CK lookup starting points
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Open ATT&CK lookupCVE-2018-20843 mapping review
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Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
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CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- USN-4040-1CVE reference · vendor-advisory, x_refsource_UBUNTU
- USN-4040-2CVE reference · vendor-advisory, x_refsource_UBUNTU
- DSA-4472CVE reference · vendor-advisory, x_refsource_DEBIAN
- 20190628 [SECURITY] [DSA 4472-1] expat security updateCVE reference · mailing-list, x_refsource_BUGTRAQ
- [debian-lts-announce] 20190629 [SECURITY] [DLA 1839-1] expat security updateCVE reference · mailing-list, x_refsource_MLIST
- FEDORA-2019-18868e1715CVE reference · vendor-advisory, x_refsource_FEDORA
- FEDORA-2019-139fcda84dCVE reference · vendor-advisory, x_refsource_FEDORA
- GLSA-201911-08CVE reference · vendor-advisory, x_refsource_GENTOO
- https://www.oracle.com/security-alerts/cpuapr2020.htmlCVE reference · x_refsource_MISC
- https://www.oracle.com/security-alerts/cpuoct2020.htmlCVE reference · x_refsource_MISC
- https://github.com/libexpat/libexpat/issues/186CVE reference · x_refsource_MISC
- https://github.com/libexpat/libexpat/pull/262CVE reference · x_refsource_MISC
- https://github.com/libexpat/libexpat/pull/262/commits/11f8838bf99ea0a6f0b76f9760c43704d00c4ff6CVE reference · x_refsource_MISC
- https://github.com/libexpat/libexpat/blob/R_2_2_7/expat/ChangesCVE reference · x_refsource_MISC
- https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=5226CVE reference · x_refsource_MISC
- https://security.netapp.com/advisory/ntap-20190703-0001/CVE reference · x_refsource_CONFIRM
- https://support.f5.com/csp/article/K51011533CVE reference · x_refsource_CONFIRM
- https://www.oracle.com/security-alerts/cpuApr2021.htmlCVE reference · x_refsource_MISC
- https://www.oracle.com/security-alerts/cpuoct2021.htmlCVE reference · x_refsource_MISC
- https://www.tenable.com/security/tns-2021-11CVE reference · x_refsource_CONFIRM
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Restriction of XML External Entity Reference
Improper Restriction of XML External Entity Reference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.