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CVE-2026-29079

Type Confusion in Lexbor Fragment Parser

8.2 HighFix available

CVE-2026-29079 is a high vulnerability (CVSS 8.2) in Lexbor, published March 13, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.28%, the 20th percentile. Fixed in php84 8.4.27-r0.

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.28%Up 0.2 points since Mar 14, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.2

Type Confusion in Lexbor Fragment Parser

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.

Record
CVE-2026-29079
CVSS 4.0
8.2 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-843
Updated
2026-11-02
EUVDEUVD-2026-12054 8.2

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.

Record
EUVD-2026-12054
CVSS 4.0
8.2 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
NVD 8.2

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.

Record
CVE-2026-29079
CVSS 4.0
8.2 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-843
Updated
2026-11-02
OSVALPINE-CVE-2026-29079 7.5

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.

Record
ALPINE-CVE-2026-29079
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-03
OSV 8.2

Type Confusion in Lexbor Fragment Parser

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.

Record
CVE-2026-29079
CVSS 4.0
8.2 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-843
Updated
2026-11-02
OSVDEBIAN-CVE-2026-29079 7.5

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.

Record
DEBIAN-CVE-2026-29079
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-29079 8.2

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.

Record
UBUNTU-CVE-2026-29079
CVSS 4.0
8.2 HighCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
php84
Alpine:v3.22
before 8.4.27-r0
8.4.27-r0
php84
Alpine:v3.23
before 8.4.21-r0
8.4.21-r0
php85
Alpine:v3.23
before 8.5.6-r0
8.5.6-r0
php85
Alpine:v3.24
before 8.5.6-r0
8.5.6-r0
lexbor
Debian:14
before 3.0.0-1, plus listed versions
2.6.0-12.6.0-23.0.0-1~exp1
3.0.0-1
lexbor
Ubuntu:26.10
All versions, plus listed versions
2.6.0-13.0.0-1
None known
lexbor
Ubuntu:26.04:LTS
All versions, plus listed versions
2.6.0-1
None known

History

History
WhenChangedSources
2026-11-03affected, aliases, referencesOSV
2026-11-02createdCVE List, EUVD, NVD, OSV

References

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