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Vulnerability · Published Mar 13, 2026 · Assigned by GitHub_M

CVE-2026-29079Type Confusion in Lexbor Fragment Parser

High 8.2

In plain English

A high-severity type confusion in lexbor from lexbor. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)8.2High
Exploit odds (30 days)0.3%top 79.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

Lexbor is a web browser engine library. Prior to 2.7.0, a type‑confusion vulnerability exists in Lexbor’s HTML fragment parser. When ns = UNDEF, a comment is created using the “unknown element” constructor. The comment’s data are written into the element’s fields via an unsafe cast, corrupting the qualified_name field. That corrupted value is later used as a pointer and dereferenced near the zero page. This vulnerability is fixed in 2.7.0.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.22php848.4.27-r0ALPINE-CVE-2026-29079
Alpine:v3.23php848.4.21-r0ALPINE-CVE-2026-29079
Alpine:v3.23php858.5.6-r0ALPINE-CVE-2026-29079
Alpine:v3.24php858.5.6-r0ALPINE-CVE-2026-29079
Debian:14lexbor3.0.0-1DEBIAN-CVE-2026-29079
Ubuntu:26.04:LTSlexborno fix listedUBUNTU-CVE-2026-29079
Ubuntu:26.10lexborno fix listedUBUNTU-CVE-2026-29079

Affected products (as reported)

VendorProductVersions
lexbor lexbor < 2.7.0

Weakness: CWE-843 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References