Vulnerability report

Active exploitation observed Confirmed confidence In CISA KEV

CVE-2025-5777

ADC

NetScaler / ADC · affected before 43.56

View live feed Monitor via API Watch CVE-2025-5777
Severity
CVSS 9.3 · Critical
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
100.0%
First observed
01 Jul 2026
Last observed
10 Sep 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2025-5777 is an unauthenticated vulnerability affecting NetScaler ADC, Gateway. Insufficient input validation leading to memory overread when the NetScaler is configured as a Gateway (VPN virtual server, ICA...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

NetScaler / ADC affected before 43.56.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

ADC

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

Vendor Product Affected Status
NetScaler ADC Before 43.56 Affected
NetScaler ADC Before 58.32 Affected
NetScaler Gateway Before 43.56 Affected
NetScaler Gateway Before 58.32 Affected
Published
17 Jun 2025
Exploitation Reported
01 Jun 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

Tags

nuclei_scanner cisa malware

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

CVE

Recorded 01 Jun 2026

A trusted third party reported exploitation.

Active exploitation observed

Previdian sensor

First observed 27 Jun 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

Used in malware

CVE

Recorded 02 Jun 2026

Malware families have been linked to exploitation of this CVE.

Proof of concept available

Nuclei Templates

Recorded 12 Jun 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
The Shadowserver First 2026-06-01 00:00 UTC
CVE 2026-06-01 10:36 UTC
CISA 2026-06-02 14:07 UTC
Previdian 2026-07-01 08:30 UTC
TheHackerNews 2026-07-02 20:20 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

32

Attempts observed

24

Unique attacker IPs

11

Attacker countries

AE · CA · DE · FI · GB · JP · NL · PL · RO · TW · US

1

Sensors observed

CVE-2025-5777 exploitation attempts over the last 74 days

Daily events observed by Previdian sensors

Updated 11 Sep 2026

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30 Jun 15 Jul 30 Jul 14 Aug 11 Sep

First observed 01 Jul 2026 · Last observed 10 Sep 2026

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Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
2
10
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

Learn about Pro API access

Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2025/CVE-2025-5777.yaml 01 Jun 2026

Risk and context

Severity, weaknesses, and research context

CVSS v4.0

9.3 Critical
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L

EPSS

100.0%

Weaknesses

Out-of-bounds Read CWE-125 Use of Uninitialized Variable CWE-457

Recent mention · Huntress Blog

CitrixBleed 2 (CVE-2025-5777) 7Steps to Dragonforce Ransomware | Huntress

Huntress has observed a series of strikingly similar intrusions beginning with CitrixBleed 2 exploitation, employing novel local privilege escalation techniques, and ending in Dragonforce ransomware.

Read full advisory

All CVSS Scores

CVSS v4.0 9.3 Critical

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L

CVSS v3.1 7.5 High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

All Mentions

Recent mention · Huntress Blog

CitrixBleed 2 (CVE-2025-5777) 7Steps to Dragonforce Ransomware | Huntress

Huntress Blog · 09 Jul 2026

Huntress has observed a series of strikingly similar intrusions beginning with CitrixBleed 2 exploitation, employing novel local privilege escalation techniques, and ending in Dragonforce ransomware.

Recent mention · TheHackerNews

Ransomware Groups Turn to Citrix Bleed 2, BYOVD, and Supply Chain Credentials

TheHackerNews · 02 Jul 2026

Threat actors associated with the Anubis ransomware operation have been observed exploiting the Citrix Bleed 2 (CVE-2025-5777) vulnerability to obtain initial access. "Although tactics differ between affiliates, common patterns emerged in tradecraft through use of legitimate Remote Management and Monitoring (RMM) tooling, credential access, and hands-on-keyboard procedures used for lateral

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

Citrix NetScaler Memory Disclosure - CitrixBleed 2

nuclei · Created Unknown

Timeline

From disclosure to observed exploitation

  1. KEV confirmed by TheHackerNews

    Exploitation attested by an external source

  2. Indicators of compromise added (43)

    Indicators of compromise recorded

  3. Observed by Previdian sensors

    Evidence-backed exploitation signal

  4. Public PoC available

    Public proof-of-concept code published

  5. First public exploitation report

    Exploit observed in malware

  6. Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  7. Nuclei template available

    Scanner coverage available

  8. KEV confirmed by CVE

    Exploitation attested by an external source

  9. Added to Previdian KEV Feed

    High-confidence, third-party attested exploitation

  10. CVE published

    Vulnerability disclosed publicly

  11. CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2025-5777

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2025-5777",
  "confidence": "Confirmed",
  "cvss_score": 9.3,
  "cvss_estimated": false,
  "epss_score": 0.99953,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 32, "sensors": 1 }
}