Shynet 0.14.0より前のバージョンでは、urldisplayおよびiconifyテンプレートフィルターでXSSが可能です。

The XSS vulnerability in Shynet allows an attacker to execute arbitrary JavaScript code within the context of a user's browser. This can be exploited to steal sensitive information, such as cookies and session tokens, which can then be used to impersonate the user. Attackers could also redirect users to malicious websites, deface the application, or inject malware. The impact is amplified if Shynet is used in a high-traffic application or handles sensitive user data, as a successful attack could affect a large number of users. While no specific real-world exploits have been publicly reported for this vulnerability, XSS vulnerabilities are consistently among the most common attack vectors.

Applications utilizing Shynet versions 0.0 through 0.14.0 are at risk. This includes web applications that rely on Shynet for templating and URL display functionality. Specifically, applications with user-controllable input that is directly rendered by the urldisplay or iconify filters are most vulnerable.

• python / server:

# Check for vulnerable Shynet versions
python -c 'import shynet; print(shynet.__version__)'

• generic web:

# Check for suspicious URL parameters in access logs
grep -i 'urldisplay|iconify' /var/log/apache2/access.log

1. 2026-04-03Disclosure

   disclosure

1. 予約済み2026-04-03
2. 公開日2026-04-03
3. EPSS 更新日2026-04-10

The primary mitigation for CVE-2026-35508 is to upgrade Shynet to version 0.14.0 or later, which contains the fix for this vulnerability. If upgrading immediately is not possible, consider implementing input validation and output encoding on user-supplied data used in the urldisplay and iconify template filters. Additionally, a Web Application Firewall (WAF) configured to detect and block XSS payloads can provide an additional layer of defense. Regularly review and update your WAF rules to ensure they are effective against the latest XSS techniques.