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CVE-2026-77088— justhtml 0.9.0 through 1.21.0 Cross-Site Scripting via code-span

Quick assessment

Affected
EmilStenstrom justhtml
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

justhtml 版本 0.9.0 至 1.21.0 在 函数中存在跨站脚本（XSS）漏洞。该漏洞源于对行内代码片段（inline code spans）的处理未将空行视为块级边界。攻击者可通过在代码或 元素文本中注入空行，破坏行内代码片段的完整性，从而导致经过安全过滤的 HTML 内容被作为未转义文本直接输出，并被符合规范的 Markdown 渲染引擎重新解析为可执行的 Markdown 语法，引发 XSS 攻击。

CVSS 6.1 · Medium EPSS 0.19% · P8

Possible ATT&CK Techniques 1 AI

T1189 · Drive-by Compromise

Affected Version Matrix 1

VendorProduct Version RangeStatus
EmilStenstrom justhtml < 0.9.0 unaffected
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I. Basic Information for CVE-2026-77088

Vulnerability Information
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Vulnerability Title
justhtml 0.9.0 through 1.21.0 Cross-Site Scripting via code-span
Source: CVE Program / CVE List V5
Vulnerability Description
justhtml versions 0.9.0 through 1.21.0 contain a cross-site scripting vulnerability in to_markdown() where inline code spans fail to account for blank lines as block boundaries. Attackers can inject blank lines into code or pre element text to break the inline span, causing sanitized HTML to be emitted unescaped and re-parsed as live Markdown by compliant renderers.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
在Web页面生成时对输入的转义处理不恰当(跨站脚本)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
EmilStenstrom justhtml 0 ~ 0.9.0 -

II. Public POCs for CVE-2026-77088

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III. Intelligence Information for CVE-2026-77088

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Vendor Advisories for CVE-2026-77088 (2)

Same Patch Batch · EmilStenstrom · 2026-08-23 · 11 CVEs total

CVE-2026-7808 9.8 CRITICAL justhtml before 1.16.0 Multiple Security Issues via Sanitization
CVE-2026-8445 9.8 CRITICAL justhtml before 1.12.0 Sanitizer Bypass via Markdown
CVE-2026-5388 9.8 CRITICAL justhtml before 1.15.0 Multiple Security Issues
CVE-2026-9769 7.5 HIGH justhtml before 1.10.0 Denial of Service via deeply nested HTML
CVE-2026-4671 7.5 HIGH justhtml before 1.18.0 Denial of Service via CSS Selector
CVE-2026-74793 6.1 MEDIUM justhtml before 3.11.0 XSS via selectedcontent projection
CVE-2026-6827 6.1 MEDIUM justhtml before 1.17.0 Multiple Cross-Site Scripting Vulnerabilities
CVE-2026-8630 6.1 MEDIUM justhtml before 1.12.0 Mutation XSS via Raw Text Elements
CVE-2026-5751 6.1 MEDIUM justhtml before 1.14.0 Mutation XSS via custom sanitization policies
CVE-2026-5389 6.1 MEDIUM justhtml before 1.13.0 XSS via code fence breakout

IV. Related Vulnerabilities

Same product: justhtml
Same vendor: EmilStenstrom
Same weakness: CWE-79

V. Comments for CVE-2026-77088

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