CVE-2026-86431

Katalog CVE

CVSS 7.2 · High EPSS 0,39%

Kerentanan Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') pada thephpleague commonmark. Skor CVSS 3.1 7.2 (High) menurut vulncheck.com.

Deskripsi (NVD)

league/commonmark (thephpleague/commonmark) versions >= 2.7.0 and < 2.9.1 contain a cross-site scripting vulnerability in the AttributesExtension. Prefixing an attribute name with a single U+000C form feed byte (e.g. {\x0Conclick="alert(1)"}) bypasses the AttributesHelper::filterAttributes() 'on*' event-handler filter because PHP's trim() does not strip U+000C, causing the attribute to be written verbatim into the output where browsers parse it as a genuine event handler. The same prefix also defeats the allow_unsafe_links check, allowing javascript: URIs through href/src attributes even when allow_unsafe_links is false. Exploitation requires processing untrusted Markdown with the AttributesExtension enabled; the injected script executes when the rendered HTML is viewed. Fixed in 2.9.1.

Rincian

Terbit di NVD

7 September 2026

Terakhir diubah

8 Oktober 2026

Status NVD

Analyzed

CVSS 3.1

7.2 (High), sumber vulncheck.com
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N · uraikan di kalkulator

Jenis kelemahan (CWE)

CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

EPSS (30 hari)

0,39% peluang dieksploitasi; lebih tinggi dari 31,0% CVE lain

Produk dan versi terdampak

> Data dari konfigurasi CPE di NVD.

Referensi dan perbaikan

• https://github.com/thephpleague/commonmark/security/advisories/GHSA-f8fg-pg57-v4j8 exploit · mitigasi · advisory vendor
• https://github.com/thephpleague/commonmark/commit/43207253ea5f14867c77c697cd3838c446cadcea patch
• https://www.vulncheck.com/advisories/commonmark-before-2.9.1-xss-via-attributesextension-form-feed-bypass patch · advisory pihak ketiga