CVE-2025-5777 — Netscaler Application Delivery Controller
HIGHCVE-2025-5777 is a high-severity (CVSS 7.5) Out-of-bounds Read vulnerability in citrix netscaler application delivery controller. It is in CISA's Known Exploited Vulnerabilities catalog (added 2025-07-10) and has been used in ransomware campaigns — treat it as actively exploited and patch now. A fix is available — see the affected versions and patch details below.
Insufficient input validation leading to memory overread when the NetScaler is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2025-07-10 — including use in ransomware campaigns. Federal agencies were required to remediate by 2025-07-11.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2025-5777.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2025-5777 by exploitation likelihood (EPSS) against impact (CVSS). In the shaded patch-first corner (EPSS 50%+, CVSS 7.0+).
Where this sits among everything scored
Of 395,249 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Counts from FIRST.org, log-scaled.
Description
Insufficient input validation leading to memory overread when the NetScaler is configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server
Affected Products
netscaler application delivery controllercitrixnetscaler gatewaycitrixResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Citrix NetScaler ADC/Gateway 14.1 - Memory Disclosure
by Yesith Alvarez · Aug 11, 2025
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every citrix netscaler application delivery controller deployment and check each version against the affected-products list above.
Fix
Apply the citrix netscaler application delivery controller security patch or hotfix for CVE-2025-5777 on the affected version, following the vendor advisory for your exact build.
Workarounds
Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.
How to detect CVE-2025-5777
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2025-5777 -u https://target- Template
- Citrix NetScaler Memory Disclosure - CitrixBleed 2
- Severity
- critical
- Impact
- Unauthenticated attackers can trigger memory overread conditions to leak sensitive information from NetScaler memory, potentially exposing session tokens and credentials similar to CitrixBleed.
- Remediation
- Apply the security patches as described in Citrix support article CTX693420 and restrict access to the NetScaler Management Interface.
Template by ProjectDiscovery nuclei-templates (watchtowr, DhiyaneshDk, darses), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2025-5777 being exploited in your environment?
Detect and block the exploit chain at execution, on systems you cannot patch yet.