Threadlinqs IntelligenceStart free

VulnerabilityCVE-2026-77643Published 2026-08-20

CVE-2026-77643 — Xapian xapian-core

mediumPublic exploit1 PoC repo

As of 2026-08-20, CVE-2026-77643 is a MEDIUM-severity vulnerability in Xapian xapian-core, CVSS v3.1 4.4, EPSS 0.1% (5.2th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-77643 as of 2026-08-20; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

CVSS v3.1
4.4/10Medium
EPSS
0.1%Higher than 5.2% of scored CVEs
CISA KEV
NoNot in the KEV catalog
Tracked threats
0None linked yet
Priority
4.4/10Threadlinqs triage score
Published
CVSS v3.1 4.4 (MEDIUM) · EPSS 0.1% (higher than 5.2% of all scored CVEs) · Priority 4.4/10 · Published 2026-08-20

Last updated:

What is CVE-2026-77643?

A cross-site scripting vulnerability in queryparser/termgenerator_internal.cc in Xapian xapian-core before 2.1.0 and before 1.4.32 exists due to incomplete HTML escaping by Xapian::MSet::snippet(). NOTE: this issue exists because of a missed corner case of CVE-2018-0499.

The record classifies CVE-2026-77643 under weakness class CWE-79. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs low-privilege credentials, needs a user to take an action first. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 46 days ago.

Severity and exploitation probability

CVSS v3.1 base score
4.4 — MEDIUM
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N
EPSS (FIRST)
0.1% probability of exploitation in the next 30 days, higher than 5.2% of all scored CVEs
CISA KEV
Not listed in the CISA Known Exploited Vulnerabilities catalog
Threadlinqs priority
4.4/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
Published
2026-08-20

Is CVE-2026-77643 being exploited?

Weaponised exploit code for CVE-2026-77643 is publicly available. 1 public proof-of-concept repository is tracked for this identifier. It currently carries a trending score of 39 in the Threadlinqs vulnerability feed.

Affected products and versions

  • Xapian: xapian-core

How to fix CVE-2026-77643

No vendor patch reference has been recorded for CVE-2026-77643 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

Threat activity tracking CVE-2026-77643

No threat campaign in the Threadlinqs corpus currently references CVE-2026-77643, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

Sources

Enriched from CVE.org, FIRST EPSS, public proof-of-concept repositories. Last verified by Threadlinqs on .

Other references