CitrixBleed 3: Inside the CVE-2026-3055 NetScaler Memory Overread Vulnerability
CVE 2026 3055 is a critical (CVSS 9.3) pre authentication memory overread vulnerability in Citrix NetScaler ADC and Gateway that allows unauthenticated attackers to leak active session tokens, LDAP credentials, and SA...
Search & fact-check with cited sources for What is CVE-2026-8451, a newly disclosed memory-disclosure vulnerability in Citrix NetScaler applCVE-2026-3055 represents the third major memory disclosure vulnerability in the Citrix NetScaler Bleed series, carrying a CVSS score of 9.3 and enabling unauthenticated session token theft.
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Create a landscape editorial hero image for this Studio Global article: Search & fact-check with cited sources for What is CVE-2026-8451, a newly disclosed memory-disclosure vulnerability in Citrix NetScaler appl. Article summary: **Correction:** The CVE you asked about — **CVE-2026-8451** — does not appear in any current security advisory or disclosure. The vulnerability being actively discussed under the "CitrixBleed 3" name is **CVE-2026-3055**. Topic tags: general, government, general web, user generated. Style: premium digital editorial illustration, source-backed research mood, clean composition, high detail, modern web publication hero. Use reference image context only for broad subject, composition, and topical grounding; do not copy the exact image. Avoid: logos, brand marks, copyrighted characters, real person likenesses, fake screenshots, UI text, readable text, watermarks, ch
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Correction: No vulnerability identified as CVE-2026-8451 exists in any current security advisory. The flaw publicly discussed under the "CitrixBleed 3" name is CVE-2026-3055 (with companion CVE-2026-4368). This article covers CVE-2026-3055 exclusively.
What Is CVE-2026-3055?
CVE-2026-3055 is a critical (CVSS 9.3) pre-authentication memory overread vulnerability in Citrix NetScaler ADC and NetScaler Gateway . It allows an unauthenticated remote attacker to leak sensitive data from appliance memory, including active session tokens and credentials. Citrix disclosed the flaw on March 23, 2026, via advisory CTX696300 . It is the third in a series of related "Bleed" vulnerabilities, following CVE-2023-4966 ("CitrixBleed") and CVE-2025-5777 ("CitrixBleed 2") .
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CVE 2026 3055 is a critical (CVSS 9.3) pre authentication memory overread vulnerability in Citrix NetScaler ADC and Gateway that allows unauthenticated attackers to leak active session tokens, LDAP credentials, and SA...
Insufficient input validation leads to an out-of-bounds memory read (CWE-125) . The appliance fails to properly validate specific parameters in SAML and WS-Federation authentication requests.
Attack Vectors
Send a malformed HTTP request to /saml/login without the AssertionConsumerServiceURL field
Send a malformed request to /wsfed/passive?wctx with an empty wctx value
These malformed requests trigger an overread, and the appliance returns memory contents in its HTTP response .
Exploitation Complexity
Exploitation is described as "trivially simple" — a single unauthenticated HTTP GET or POST request is sufficient . No special tools, authentication, or user interaction is required .
Data Leaked
Active session tokens: NSC_AAAC, NSC_TMAS, NSC_TASS cookies
LDAP bind credentials
SAML signing keys
Other secrets present in process memory
Leaked data appears base64-encoded inside the NSC_TASS response .
Exploitation Timeline
Date
Event
2026-03-23
Citrix publishes advisory CTX696300 and releases patches
2026-03-27
watchTowr Labs confirms active reconnaissance and exploitation from known threat actor IPs — just 4 days after disclosure
2026-03-30
Multiple security firms publicly confirm active in-the-wild exploitation
~2026-03-31
CISA adds CVE-2026-3055 to its Known Exploited Vulnerabilities (KEV) catalog
2026-04–May
Mass scanning observed; proof-of-concept and exploit code circulate widely
Early June 2026
Large-scale exploitation campaign enters a new wave, targeting unpatched appliances at scale
Attack Infrastructure
Residential Proxy Networks
Attackers used thousands of residential proxy IPs to conduct reconnaissance and exploitation, making source-IP blocking ineffective .
Known Threat Actor IPs
watchTowr reported specific source IPs tied to known threat actor groups beginning exploitation on March 27 .
Automated Scanning
GreyNoise and other threat intelligence platforms detected mass scanning for vulnerable endpoints (/saml/login, /wsfed/passive) within days of disclosure .
Impact
Session Hijacking and MFA Bypass
Attackers can steal active session tokens from memory and reuse them to authenticate as any active user, completely bypassing multi-factor authentication .
Credential Theft
LDAP bind credentials and SAML signing keys in memory can also be exfiltrated, enabling lateral movement and persistent access .
Identity-Path Compromise
Because the flaw leaks material from the identity provider path, rotation of all secrets "touched" by that path is required post-incident .
Scope
All NetScaler ADC and NetScaler Gateway instances configured as a Gateway or AAA virtual server (internet-facing identity provider role) are affected .
Mitigation Recommendations
1. Patch Immediately (24–48 Hours for Internet-Facing Appliances)
Apply the fixed versions released on March 23, 2026, per Citrix advisory CTX696300:
NetScaler ADC & Gateway 14.1-66.59 or later
NetScaler ADC & Gateway 14.1-60.58
NetScaler ADC & Gateway 13.1-62.23 or later
NetScaler ADC 13.1-FIPS / NDcPP 13.1-37.262
2. Rotate All Session Tokens
After patching, invalidate all existing NSC_AAAC, NSC_TMAS, and NSC_TASS cookies and force re-authentication for every user .
3. Rotate All Secrets in the Identity Path
LDAP bind credentials, SAML signing keys, service-account passwords, and any other secrets that were present in appliance memory during the exposure window .
4. Deploy Detection Signatures
Monitor for:
Anomalous requests to /saml/login and /wsfed/passive endpoints
Unusually large HTTP responses
Unexpected session token reuse
5. Network Segmentation
Isolate NetScaler appliances from the internal network where possible, and limit outbound connectivity from the appliance .
6. Consider Temporary Workarounds
If patching is delayed, disable SAML and WS-Federation endpoints on the Gateway or restrict access to them via WAF/reverse-proxy rules. Patching is the only complete fix .
reddit.comCVE-2026-3055 & CVE-2026-4368: Inside the NetScaler "CitrixBleed 3" Memory Overread
