Over 1,200 Citrix NetScaler ADC and NetScaler Gateway home equipment uncovered on-line are unpatched towards a important vulnerability believed to be actively exploited, permitting menace actors to bypass authentication by hijacking consumer classes.
Tracked as CVE-2025-5777 and known as Citrix Bleed 2, this out-of-bounds reminiscence learn vulnerability outcomes from inadequate enter validation, enabling unauthenticated attackers to entry restricted reminiscence areas.
The same Citrix safety flaw, dubbed “CitrixBleed,” was exploited in ransomware assaults and breaches focusing on governments in 2023 to hack NetScaler units and transfer laterally throughout compromised networks.
Efficiently exploiting CVE-2025-5777 may enable menace actors to steal session tokens, credentials, and different delicate information from public-facing gateways and digital servers, enabling them to hijack consumer classes and bypass multi-factor authentication (MFA).
In a June 17 advisory, Citrix warned clients to terminate all energetic ICA and PCoIP classes after upgrading all their NetScaler home equipment to a patched model to dam potential assaults.
On Monday, safety analysts from the web safety nonprofit Shadowserver Basis have found over the weekend that 2,100 home equipment had been nonetheless susceptible to CVE-2025-5777 assaults.
Whereas Citrix has but to verify that this safety flaw is being exploited within the wild, saying that “at present, there isn’t any proof to counsel exploitation of CVE-2025-5777,” cybersecurity agency ReliaQuest reported on Thursday with medium confidence that the vulnerability is already being abused in focused assaults.
“Whereas no public exploitation of CVE-2025-5777, dubbed ‘Citrix Bleed 2,’ has been reported, ReliaQuest assesses with medium confidence that attackers are actively exploiting this vulnerability to realize preliminary entry to focused environments,” ReliaQuest warned.
ReliaQuest recognized indicators suggesting post-exploitation exercise following unauthorized Citrix entry, together with a hijacked Citrix net session indicating a profitable MFA bypass try, session reuse throughout a number of IP addresses (together with suspicious ones), and LDAP queries linked to Lively Listing reconnaissance actions.
Shadowserver additionally discovered over 2,100 NetScaler home equipment unpatched towards one other important vulnerability (CVE-2025-6543), which is now being exploited in denial-of-service (DoS) assaults.
With each flaws being tagged as important severity vulnerabilities, directors are suggested to deploy the most recent patches from Citrix as quickly as doable. Firms must also evaluate their entry controls and monitor Citrix NetScaler home equipment for suspicious consumer classes and exercise.
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