justhtml versions before 1.13.0 contain a cross-site scripting vulnerability in the to_markdown() function when serializing attacker-controlled pre content. Attackers can place backticks inside sanitized pre elements to break out of fixed-length code fences, allowing raw HTML to execute when the generated Markdown is rendered by CommonMark or GFM-style renderers.
{
"cna_assigner": "VulnCheck",
"cwe_ids": [
"CWE-80"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5389.json"
}{
"extracted_events": [
{
"range": [
{
"introduced": "0"
},
{
"fixed": "1.13.0"
}
],
"source": "AFFECTED_FIELD",
"strategy": "StandardRange"
},
{
"range": [
{
"introduced": "0"
},
{
"fixed": "1.13.0"
}
],
"source": "DESCRIPTION"
}
]
}