Citrix NetScaler Out-of-Bounds Read Vulnerability
Citrix · NetScaler
Citrix NetScaler ADC and NetScaler Gateway contain an insufficient input validation flaw, classified as an out-of-bounds read, in the component that handles them when configured as a SAML identity provider. An attacker with network access can trigger memory overread without authentication, user interaction, or any special configuration beyond the SAML IDP setup.
Insufficient input validation in NetScaler ADC and NetScaler Gateway when configured as a SAML IDP leading to memory overread
- Exploited
- Yes, in CISA KEV
- Reports
- 0
- Tactics
- 2/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited 6 days after disclosure. Public exploit code (Metasploit) was available the same day.
- First seen exploitedVulnCheck KEV evidence+6 days
- Added to CISA KEVEU database agrees+7 days
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
2 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain order, 2 cited passages 2Initial AccessTA0001
Network-reachable appliance input validation flaw
Insufficient input validation in NetScaler ADC and NetScaler Gateway
CollectionTA0009
Memory overread discloses sensitive data locally
leading to memory overread
Detection
0 rules for this CVE · 163 general rules for its techniquesRules for this CVE
0Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2026-3055 directly.CVE-specific rules are not available in this build. Search SigmaHQ ↗
General rules for this CVE’s techniques
These detect the technique in general, not this specific vulnerability.
Exploit Public-Facing ApplicationT1190149 general rules
- Arcadyan Router Exploitationscriticaltest
- Citrix ADS Exploitation CVE-2020-8193 CVE-2020-8195criticaltest
- Citrix Netscaler Attack CVE-2019-19781criticaltest
- Confluence Exploitation CVE-2019-3398criticaltest
- CVE-2010-5278 Exploitation Attemptcriticaltest
- CVE-2020-0688 Exchange Exploitation via Web Logcriticaltest
- CVE-2020-10148 SolarWinds Orion API Auth Bypasscriticaltest
- CVE-2020-5902 F5 BIG-IP Exploitation Attemptcriticaltest
Data from Local SystemT100514 general rules
- OpenCanary - SMB File Open Requesthightest
- Potential Conti Ransomware Database Dumping Activity Via SQLCmdhightest
- SQLite Chromium Profile Data DB Accesshightest
- SQLite Firefox Profile Data DB Accesshightest
- VeeamBackup Database Credentials Dump Via Sqlcmd.EXEhightest
- Script Interpreter Spawning Credential Scanner - Linuxhighexperimental
- Script Interpreter Spawning Credential Scanner - Windowshighexperimental
- Shai-Hulud NPM Package Malicious Exfiltration via Curlhighexperimental
Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.
What security researchers reported
Not named in any threat report yetAlso mentioned in 50 community threat pulses (AlienVault OTX)
Weaker evidencePulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.
- Actively_Exploited_Kev | Oct 31, 202630 Oct 2026
- Actively_Exploited_Kev | Oct 30, 202629 Oct 2026
- Actively_Exploited_Kev | Oct 29, 202628 Oct 2026
- Actively_Exploited_Kev | Oct 28, 202627 Oct 2026
- Actively_Exploited_Kev | Oct 27, 202626 Oct 2026
- Actively_Exploited_Kev | Oct 24, 202623 Oct 2026
- 44 more on OTX