CitrixBleed-style memory overread in NetScaler ADC/Gateway SAML IdP
CVE-2026-8451 is a high-severity insufficient input validation vulnerability in Citrix NetScaler ADC and NetScaler Gateway that can cause an out-of-bounds memory overread when the appliance is configured as a SAML Identity Provider (IdP). Available reporting indicates the flaw is in NetScaler's parsing of SAML authentication requests sent to the /saml/login endpoint, where a client-supplied base64-encoded XML document is processed by a custom XML parser. Researchers reported that malformed SAML input, including mishandled or unterminated attribute values, can trigger the overread during parsing. Leaked memory fragments are reportedly returned in the NSC_TASS response cookie. The issue has been described as belonging to the same general class as prior "CitrixBleed" memory disclosure flaws. Affected versions include NetScaler ADC and NetScaler Gateway 14.1 before 14.1-72.61, 13.1 before 13.1-63.18, NetScaler ADC FIPS before 14.1-72.61 FIPS, and NetScaler ADC FIPS/NDcPP before 13.1-37.272.
Are you exposed to this one?
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos (1 hidden).
Small standalone Python exploit repository containing one executable script and one README. The main file, watchTowr-vs-Netscaler-CVE-2026-8451.py, is an operational proof-of-concept for CVE-2026-8451 affecting Citrix NetScaler ADC/Gateway. It uses requests with a custom SSL adapter that lowers OpenSSL security level to improve compatibility with NetScaler TLS configurations, disables certificate validation warnings, and repeatedly sends crafted POST requests to the target's /saml/login endpoint. The exploit builds malformed SAML AuthnRequest XML with varying whitespace lengths to influence heap allocation behavior, base64-encodes the request, percent-encodes the resulting bytes, and submits it as the SAMLRequest parameter. If exploitation succeeds, the appliance returns an NSC_TASS cookie whose decoded contents may contain leaked memory; the script searches for the ACSURL= marker and prints trailing bytes as a hexdump. The README documents usage, shows sample leaked output, and lists affected NetScaler versions from the Citrix advisory. Overall purpose: trigger and demonstrate a remote memory overread over HTTPS against vulnerable NetScaler SAML login functionality.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
42 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A high-severity vulnerability in Citrix NetScaler ADC and NetScaler Gateway related to improper memory handling and insufficient input validation that can be exploited to cause denial-of-service or memory overflow conditions.
A high-severity out-of-bounds read information disclosure vulnerability in Citrix NetScaler’s XML parser that can leak restricted memory and is described as CitrixBleed-style.
An insufficient input validation flaw in Citrix NetScaler ADC and NetScaler Gateway that can cause memory overread when configured as a SAML IdP.
A critical vulnerability addressed by Citrix in NetScaler ADC, NetScaler Gateway, and related FIPS/NDcPP editions.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.