Stored XSS via unescaped snippet fast path
Published Aug 20, 2026 · Updated Aug 20, 2026
Cross-site scripting in Xapian xapian-core before 1.4.32 and 2.1.0 allows attackers to inject script into HTML search results via stored content. In Xapian::MSet::snippet() in queryparser/termgenerator_internal.cc, a fast path returns text unchanged when hi_start and hi_end are empty and text.size() is within length, so append_escaping_xml() never runs despite the API contract promising HTML-safe output. Exposure requires an application that indexes untrusted content, calls snippet() with empty highlight markers, and renders the returned snippet as HTML; Xapian states that this calling pattern is unusual, but affected integrations can expose stored XSS in the embedding web application.
Summary
What happened
Cross-site scripting in Xapian xapian-core before 1.4.32 and 2.1.0 allows attackers to inject script into HTML search results via stored content. In Xapian::MSet::snippet() in queryparser/termgenerator_internal.cc, a fast path returns text unchanged when hi_start and hi_end are empty and text.size() is within length, so append_escaping_xml() never runs despite the API contract promising HTML-safe output. Exposure requires an application that indexes untrusted content, calls snippet() with empty highlight markers, and renders the returned snippet as HTML; Xapian states that this calling pattern is unusual, but affected integrations can expose stored XSS in the embedding web application.
The record
- CVE
- CVE-2026-77643
- Published
- Aug 20, 2026
- Updated
- Aug 20, 2026
- Vendor
- Xapian
- Product
- xapian-core
- Classifications
- CWE-79, T1189
- Attack vector
- network
- Privileges
- Unavailable
Timeline
How it unfolded
- Aug 20, 2026CVE publishedPublication date reported by the CVE source.
- Aug 20, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <1.4.32
- Affected versionversion=2.0.0 <2.1.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- MSet::snippet() returns unescaped text when hi_start and hi_end are both emptyproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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