CVE-2026-49825: lxml: javascript: URL bypass in Cleaner via xlink:href

highCVSS 8.2CVE-2026-49825

CSIRTS triage

vendor: lxml product: lxml Cross-site scripting

What: The Cleaner component in lxml fails to properly sanitize javascript: URLs in xlink:href attributes, allowing XSS injection.
Who is affected: Applications using lxml's Cleaner to sanitize HTML/XML with SVG content.
Urgency: High severity (CVSS 8.2) but not yet exploited; patching should be prioritized within standard maintenance windows.
Action: Update lxml to a patched version that properly removes or sanitizes javascript: URLs in xlink:href attributes.

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

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Details

Source: Microsoft Security Response Center (INTL · vendor-psirt · site)
Severity: high — CVSS 8.2
Published: 2026-08-11
Exploitation: Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-49825

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-2026-498250.24% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 15% of all EPSS-scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-49825	coverage & exploitation status	NVD · CVE.org

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