CVE-2026-33347
league/commonmark has an embed extension allowed_domains bypass
MEDIUM 6.3
At a glance
- Source
- NVD
- EPSS
- EPSS 0.25 % · percentile 16 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- GitHub_M
- NVD status
- Analyzed
Description
league/commonmark is a PHP Markdown parser. From version 2.3.0 to before version 2.8.2, the DomainFilteringAdapter in the Embed extension is vulnerable to an allowlist bypass due to a missing hostname boundary assertion in the domain-matching regex. An attacker-controlled domain like youtube.com.evil passes the allowlist check when youtube.com is an allowed domain. This issue has been patched in version 2.8.2.
Weaknesses (CWE)
- CWE-79 — Improper Neutralization of Input During Web Page Generation
- CWE-185 — Incorrect Regular Expression
- CWE-918 — Server-Side Request Forgery
References
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 4.0 | MEDIUM 6.3 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N | GitHub_M |
| CVSS 4.0 | MEDIUM 6.3 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/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 | NVD · security-advisories@github.com (Secondary) |
| CVSS 3.1 | MEDIUM 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N | NVD · nvd@nist.gov (Primary) |
Advisories
- GHSA-hh8v-hgvp-g3f5 — league/commonmark has an embed extension allowed_domains bypass
European references
- ENISA EUVD · EUVD-2026-20079
- GCVE · GCVE-0-2026-33347
Affected configurations (NVD CPE)
cpe:2.3:a:thephpleague:commonmark:*:*:*:*:*:*:*:*≥ 2.3.0 < 2.8.2
Affected products
| Product | Versions |
|---|---|
| thephpleague · commonmark | affected >= 2.3.0, < 2.8.2 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |