CVE-2026-48591
Stored XSS via unescaped HTML attribute values in earmark
Weakness Type (CWE)
CWE-83 — CWE-83 Improper Neutralization of Script in Attributes in a Web Page
CAPEC
Vulnerability description
Improper Neutralization of Script in Attributes in a Web Page vulnerability in pragdave earmark allows stored cross-site scripting via unescaped HTML attribute values.
'Elixir.Earmark.Transform':_make_att1/2 in lib/earmark/transform.ex splices attribute values verbatim between two literal " bytes: [" ", name, "=\"" , value, "\""]. Text nodes are routed through the existing escape function which encodes " as ", but attribute values never visit that path. A markdown link whose URL or title contains a bare " closes the attribute early and lets the trailing bytes be parsed by the browser as fresh HTML attributes. For example, [click](http://example.com/?a=x" onerror="alert(1)) renders as <a href="http://example.com/?a=x" onerror="alert(1)">click</a>, executing arbitrary JavaScript in the victim's browser.
The earmark library is no longer maintained and has been retired on Hex. No patched version will be released. All releases from 1.4.1 onward are affected, and users should migrate to a maintained Markdown library such as MDEx.
This issue affects earmark from 1.4.1 onward.
Affected
pkg:hex/earmark
| Module | Source File | Routine |
|---|---|---|
Earmark.Transform
|
lib/earmark/transform.ex
|
Earmark.Transform._make_att1/2
|
pkg:github/pragdave/earmark
| Module | Source File | Routine |
|---|---|---|
Earmark.Transform
|
lib/earmark/transform.ex
|
Earmark.Transform._make_att1/2
|
| Status | Type | Version | Changes / Fixed in |
|---|---|---|---|
| affected | git ⓘ | 8236a0570b
|
no fix available |
Workarounds
Migrate to a maintained Markdown library such as MDEx. The earmark package has been retired on Hex and no patched release will be made.
References
Credits
- Finder: Peter Ullrich
- Remediation developer: Robert Dober
- Analyst: Jonatan Männchen / EEF
CVE record as JSON:
GET /cves/CVE-2026-48591.json
OSV record as JSON:
GET /osv/EEF-CVE-2026-48591.json