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Citrix disclosed CVE-2025-5777 in NetScaler ADC and NetScaler Gateway alongside CVE-2025-5349, warning that affected appliances could be exposed to remote exploitation. Public tracking by ENISA’s EUVD and subsequent reporting identified CVE-2025-5777 as CitrixBleed 2, linking the issue to session exposure risks on internet-facing NetScaler deployments and raising concern for organizations that rely on the products for remote access.
After the advisory, proof-of-concept and scanning tools for CVE-2025-5777 appeared on GitHub, including repositories explicitly branded as CitrixBleed 2 scanners. The rapid publication of exploit-related code lowered the barrier for attackers to identify vulnerable devices, increasing urgency for defenders to patch NetScaler systems, review exposed gateways, and monitor for signs of session theft or unauthorized access.
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6 events from the most recent confirmed update back to the earliest known activity.
CSO Online reported that a CitrixBleed-like NetScaler vulnerability was seeing exploit attempts in the wild. This marks an escalation from disclosure and research activity to observed attack activity.
Another GitHub repository dedicated to CVE-2025-5777 was published, indicating continued public sharing of technical material related to the vulnerability. This suggests ongoing community analysis and tooling development around the issue.
A GitHub repository named 'citrix_bleed_2' was published with a proof-of-concept scanner for CVE-2025-5777. The release of public scanning code lowered the barrier to identifying potentially vulnerable NetScaler systems.
SOCRadar published analysis describing CVE-2025-5777 as 'CitrixBleed 2' and warning that NetScaler Gateway devices were exposed to remote exploitation. This represents a public escalation in awareness around the vulnerability's severity and attack potential.
ENISA's EU Vulnerability Database added an entry for CVE-2025-5777, reflecting broader public cataloging of the issue after vendor disclosure. The listing indicates the vulnerability had entered formal vulnerability-tracking channels.
Citrix published a security bulletin for NetScaler ADC and NetScaler Gateway covering CVE-2025-5777 and CVE-2025-5349. This marks the public vendor disclosure of the vulnerability and the availability of official remediation guidance.
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Multiple severe vulnerabilities in **Citrix ADC** and **NetScaler Gateway** exposed organizations to unauthenticated compromise, including remote code execution in `CVE-2019-19781` and `CVE-2023-3519`, as well as memory disclosure in `CVE-2023-4966` (**CitrixBleed**) and the later `CVE-2025-5777` variant. Public reporting showed that `CVE-2019-19781` could be exploited through crafted HTTP requests that abused directory traversal and template parsing to execute commands on vulnerable appliances, while research on `CVE-2023-3519` examined another critical path to code execution on internet-facing Citrix infrastructure.
Jun 29, 2026
Researchers detailed how ransomware operators linked to **LockBit** exploited Citrix NetScaler ADC and Gateway appliances through the original **CitrixBleed** flaw, `CVE-2023-4966`, using stolen session data to support follow-on access and affiliate infrastructure operations. An OSINT analysis built from joint government and Boeing-published indicators identified additional suspected LockBit infrastructure spanning command-and-control, remote management, FTP, RDP, and OpenVPN services, with recurring hosting patterns and overlaps with tooling and infrastructure previously associated with **Akira**, **Avaddon**, **Cerber**, **BumbleBee**, **Raccoon Stealer**, **RecordBreaker**, **SolarMarker**, **8Base**, and **ShadowSyndicate**. A later root-cause analysis of **CitrixBleed 2**, `CVE-2025-5777`, showed that a malformed POST request to `/p/u/doAuthentication.do` can trigger an out-of-bounds memory disclosure on vulnerable NetScaler devices, leaking up to `0x7F` bytes per request in an authentication failure response. Researchers warned that exposed memory may include credentials, session cookies, and private keys, making the bug a low-noise path to unauthenticated access similar in impact to the earlier CitrixBleed incidents; Citrix issued fixes and defenders were urged to patch immediately, invalidate sessions, reset credentials, rotate certificates and secrets where needed, and review telemetry for LockBit-related indicators, while broad community IOC feeds for suspected **LockBit 5.0** activity have also circulated with explicit false-positive caveats.
Jun 29, 2026
Citrix released fixes for six vulnerabilities in **NetScaler ADC** and **NetScaler Gateway**, including **CVE-2026-8451**, a high-severity out-of-bounds read flaw that can leak sensitive memory from appliances configured as a **SAML Identity Provider**. The bug affects customer-managed NetScaler ADC, Gateway, and related **FIPS/NDcPP** variants, and can expose memory contents in the `NSC_TASS` cookie via malformed requests to the `/saml/login` endpoint. Other patched issues include **CVE-2026-8452**, **CVE-2026-8655**, **CVE-2026-10816**, **CVE-2026-10817**, and **CVE-2026-13474**, covering risks such as arbitrary file reads, memory corruption, and denial of service, including a new **HTTP/2 Bomb** attack. Security researchers and defenders reported that **CVE-2026-8451** was exploited in the wild less than 24 hours after public disclosure, with Lupovis observing threat actors scanning exposed NetScaler systems and sending exploit payloads immediately after receiving valid `200 OK` responses. The observed activity matched public technical details released by watchTowr, using malformed SAML `AuthnRequest` data padded to trigger the overread condition. Government and industry advisories urged organizations to patch immediately, disable **SAML IdP** where patching is not possible, review `/saml/login` traffic and `NSC_TASS` cookie values for signs of compromise, restrict management exposure, and follow Citrix incident guidance if exploitation is suspected.
Jul 9, 2026