[UPDATE] [medium] libxml2: Vulnerability allows denial of service

mediumCVE-2026-6653

A remote, anonymous attacker can exploit a vulnerability in libxml2 to conduct a denial of service attack.

CSIRTS triage

vendor: libxml2 product: libxml2 Denial of service

What: A vulnerability allows a remote, anonymous attacker to conduct a denial of service attack.
Who is affected: Deployments of libxml2 are affected.
Urgency: Remediation is medium urgency as exploitation is possible but not currently active.
Action: Update to the latest version of libxml2.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: CERT-Bund (BSI) Security Advisories (DE · national-cert · site)
Severity: medium
Published: 2026-09-02
Exploitation: Not in CISA KEV at last sync
Language: Machine-translated to English — verify against the original

Original advisory: https://wid.cert-bund.de/portal/wid/securityadvisory?name=WID-SEC-2026-2037

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Low exploitation riskCVE-2026-66530.36% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 29% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-6653	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

high[NEW] [high] Hitachi Energy RTU500: Multiple Vulnerabilitiescert-bund
high[NEW] [high] Meinberg LANTIME: Multiple vulnerabilitiescert-bund

Recent advisories for libxml2

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

high[UPDATE] [hoch] libxml2: Mehrere Schwachstellen ermöglichen Denial of Servicecert-bund · 2026-09-10
high[NEU] [hoch] libxml2: Schwachstelle ermöglicht Denial of Servicecert-bund · 2026-09-09
highCVE-2026-74860: A flaw was found in libxml2 with Python bindings enabled. A remote attacker could exploit this…nvd · 2026-09-08
mediumCVE-2026-86139: In libxml2 before 2.15.4, xmlURIEscapeStr in uri.c has an integer overflow.msrc · 2026-09-08
mediumCVE-2026-86143: In xmlIO in libxml2 before 2.15.4, an inconsistency in xmlOutputWriteCallback and xmlBufUse ca…msrc · 2026-09-08
mediumCVE-2026-86138: In libxml2 before 2.15.4, xmlDictAddQString in dict.c has an integer overflow and resultant he…msrc · 2026-09-08