cbcvebase.
CVE-2025-5777
published 2025-06-17

CVE-2025-5777: 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…

PriorityP193high7.5CVSS 3.1
AVNACLPRNUINSUCHINAN
KEVITWEXPLOITRansomware
CISA Known Exploited Vulnerabilitydue 2025-07-11
Exploited in the wild
EPSS
99.95%
100.0th percentile
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

17 ranges
VendorProductVersion rangeFixed in
citrixcitrix_adm
citrixcitrix_hypervisor
citrixcitrix_virtual_apps_and_desktops
citrixendpoint_management
citrixnetscaler_adc
citrixnetscaler_application_delivery_controller>= 12.1 < 12.1-55.32812.1-55.328
citrixnetscaler_application_delivery_controller>= 13.1 < 13.1-37.23513.1-37.235
citrixnetscaler_application_delivery_controller>= 13.1 < 13.1-58.3213.1-58.32
citrixnetscaler_application_delivery_controller>= 14.1 < 14.1-43.5614.1-43.56
citrixnetscaler_gateway
citrixnetscaler_gateway>= 13.1 < 13.1-58.3213.1-58.32
citrixnetscaler_gateway>= 14.1 < 14.1-43.5614.1-43.56
citrixxenserver
netscaleradc>= 13.1 < 58.3258.32
netscaleradc>= 14.1 < 43.5643.56
netscalergateway>= 13.1 < 58.3258.32
netscalergateway>= 14.1 < 43.5643.56

Detection & IOCsextracted from sources · hover to see the quote

cookieNSC_TASS
url/saml/login
url/cgi/GetAuthMethods
  • Monitor for requests to /cgi/GetAuthMethods as a reconnaissance indicator — attackers use this endpoint to fingerprint authentication methods and determine if NetScaler is configured as a SAML IDP prior to exploitation.
  • Detect exploitation attempts by monitoring for SAMLRequest payloads to /saml/login that omit the AssertionConsumerServiceURL field; a vulnerable device will respond with memory contents Base64-encoded in the NSC_TASS cookie.
  • Detect exploitation of the /wsfed/passive endpoint by monitoring for requests containing a 'wctx' query string parameter with no value and lacking the '=' symbol; a vulnerable device will leak memory Base64-encoded in the NSC_TASS cookie.
  • On a patched NetScaler, a request to /saml/login with a missing AssertionConsumerServiceURL will return the response: 'Parsing of presented Assertion failed; Please contact your administrator.' — use this to distinguish patched vs. vulnerable instances.
  • After patching CVE-2025-5777, kill all active sessions to prevent session token hijacking using the commands: kill icaconnection -all; kill pcoipConnection -all; kill aaa session -all; kill rdp connection -all; clear lb persistentSessions.
  • Look for signs of compromise on NetScaler devices including atypical file creation dates, duplicate file names with different extensions, and the absence of PHP files in expected folders.
  • CVE-2025-5777 (CitrixBleed 2) enables unauthenticated attackers to steal session tokens from memory, allowing session hijacking and MFA bypass on devices configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server.
  • ·CVE-2025-5777 only affects NetScaler devices configured as a Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server — devices not in these configurations are not vulnerable.
  • ·Proof-of-concept exploits for CVE-2025-5777 were released less than two weeks after disclosure, and active exploitation in zero-day attacks was detected weeks before PoC release — patch urgency is high.

CVSS provenance

nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
nvdv4.09.3CRITICALCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vulncheck9.3CRITICAL
cisa9.3CRITICAL
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