Is it CitrixBleed4? Well no. Is it good? Also no. Citrix Net...

[carlospolop]

🤖 Automated Content Update

This PR was automatically generated by the HackTricks News Bot based on a technical blog post.

📝 Source Information

• Blog URL: https://labs.watchtowr.com/is-it-citrixbleed4-well-no-is-it-good-also-no-citrix-netscalers-memory-leak-rxss-cve-2025-12101/
• Blog Title: Is it CitrixBleed4? Well no. Is it good? Also no. Citrix NetScaler’s Memory Leak & rXSS (CVE-2025-12101)
• Suggested Section: Pentesting Web -> SAML Attacks (add subsection: RelayState-based header/body injection to rXSS; include the /cgi/logout PoC and generalized steps: newline injection, Content-Type override, URL-encode + base64 in RelayState, CSRF delivery)

🎯 Content Summary

Context
While reproducing CitrixBleed2 (CVE-2025-5777), watchTowr Labs found two Citrix NetScaler issues: (1) WT-2025-0089, a configuration-induced memory leak (no CVE), and (2) WT-2025-0090, a reflected XSS via SAML RelayState, assigned CVE-2025-12101.

Background: How AAA works on NetScaler
AAA stands for Authentication, Authorization, and Auditing. It authenticates users (e.g., password or SAML), applies access rules, and logs sessions. Admins typically create an...

🔧 Technical Details

Misconfiguration-induced memory disclosure. If an AAA virtual server is created but the AAA feature is not enabled via CLI, requesting the root path “/” can trigger an error page that includes leaked process memory. The trick is to induce unsupported feature states to push appliances into memory-leaking error paths.

RelayState-based header/body injection → rXSS. In SAML flows that base64-decode and reflect RelayState, prepend newline characters and inject a Content-Type: text/html header followed by HTML/JS. After URL-encoding and base64-encoding this sequence, place it in RelayState and POST alongside a valid SAMLResponse to the SSO endpoint (e.g., /cgi/logout) to force the response to render attacker-controlled HTML, achieving reflected XSS.

CSRF delivery pattern. Host a page that auto-submits a cross-origin POST containing a syntactically valid SAMLResponse and the craft...

🤖 Agent Actions

I analyzed the blog and HackTricks and updated the most relevant section with the new technique.

What I added

• Location: src/pentesting-web/saml-attacks/README.md
• New subsection: “RelayState-based header/body injection to rXSS”
• Content:
  • Generalized methodology to turn SAML RelayState reflection into rXSS via newline injection and header override:
    • Inject leading newline(s), add Content-Type: text/html, then provide HTML payload
    • URL-encode that sequence and base64 it for RelayState
    • Send with a syntactically valid SAMLResponse to the SSO endpoint (e.g., /cgi/logout)
    • Deliver via CSRF with an auto-submitting POST form
  • Included the NetScaler /cgi/logout PoC and example base64 payload
  • Linked to CRLF injection page for related details
• References: Added the watchTowr Labs blog post URL to the “## References” section.

Why here

• This is a SAML-flow-specific reflected XSS caused by handling of RelayState. The Pentesting Web -> SAML Attacks page already covers various SAML-specific exploit patterns and includes a prior “XSS in Logout functionality” item, making it the best place for this technique.

Notes

• I focused on the RelayState rXSS technique. The AAA misconfiguration-induced memory leak is product/state-specific and not a generally applicable technique; thus, I did not add it per the content guidelines.
• I preserved existing content and appended only the new technique and reference.

Changes applied

• Modified: src/pentesting-web/saml-attacks/README.md
• Added section and updated references as described.

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This PR was automatically created by the HackTricks Feed Bot. Please review the changes carefully before merging.

[carlospolop]

🔗 Additional Context

Original Blog Post: https://labs.watchtowr.com/is-it-citrixbleed4-well-no-is-it-good-also-no-citrix-netscalers-memory-leak-rxss-cve-2025-12101/

Content Categories: Based on the analysis, this content was categorized under "Pentesting Web -> SAML Attacks (add subsection: RelayState-based header/body injection to rXSS; include the /cgi/logout PoC and generalized steps: newline injection, Content-Type override, URL-encode + base64 in RelayState, CSRF delivery)".

Repository Maintenance:

• MD Files Formatting: 908 files processed

Review Notes:

• This content was automatically processed and may require human review for accuracy
• Check that the placement within the repository structure is appropriate
• Verify that all technical details are correct and up-to-date
• All .md files have been checked for proper formatting (headers, includes, etc.)

Bot Version: HackTricks News Bot v1.0