Security readout for executives and security teams
Plain-English summary
CVE-2025-5777 is a critical NetScaler flaw that can expose memory from internet-facing access systems without authentication or user interaction. CISA lists it as actively exploited. Compromise could affect confidential information and the integrity or availability of connected services. Organizations using affected Gateway or AAA configurations should treat remediation and incident review as urgent.
Executive priority
Immediate. Identify owners and affected appliances today, prioritize internet-facing Gateway and AAA services, apply vendor updates, and conduct compromise assessment. Because exploitation is documented, patching alone should not be treated as proof that earlier exposure caused no harm.
Technical view
Insufficient input validation causes an out-of-bounds memory read in NetScaler ADC and Gateway 13.1 and 14.1 when configured as a Gateway or AAA virtual server. The CVSS 4.0 score is 9.3, with network access, low complexity, no privileges, and no user interaction. The supplied sources do not specify exact vulnerable or fixed builds.
Likely exposure
Exposure is limited to NetScaler ADC or Gateway 13.1 and 14.1 operating as VPN, ICA Proxy, CVPN, RDP Proxy, or AAA virtual servers. Internet-facing deployments are especially concerning. The bundle does not provide enough build-level detail to determine whether any individual appliance is vulnerable.
Exploitation context
Active exploitation is confirmed by inclusion in CISA's Known Exploited Vulnerabilities catalog. A cited technical report says exploitation began in mid-June 2025. The supplied evidence does not quantify affected organizations or establish that every exposed appliance was compromised.
Researcher notes
The record maps the issue to CWE-125 and CWE-457. Configuration is central to exposure, while the supplied version data identifies only 13.1 and 14.1, not point builds. Validate against the current vendor matrix. Avoid interpreting public exploit discussion as proof of compromise without appliance-specific telemetry.
Mitigation direction
- Check every appliance against the exact affected and fixed build matrix in NetScaler advisory CTX693420.
- Apply the vendor-prescribed security update immediately to vulnerable Gateway and AAA deployments.
- Restrict external access to affected services until updating is complete where operationally feasible.
- Follow vendor and incident-response guidance for session invalidation and credential protection after suspected exposure.
Validation and detection
- Inventory NetScaler ADC and Gateway versions, builds, and enabled virtual-server configurations.
- Confirm installed builds against CTX693420 rather than relying only on major version numbers.
- Verify the vendor-prescribed update is installed and the appliance restarted if required.
- Review security telemetry for anomalous access or suspected memory disclosure beginning in mid-June 2025.
- Escalate suspicious findings for incident response and assess connected systems for secondary impact.
Public sources used
The source record changed after analysis: Material source record changed after analysis.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-125: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-457: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2025-5777 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.3 (4.0)
- Known Exploited
- Yes
- Published
Vector: 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
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CISA KEV status
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
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——CitrixVulnerability scoring details
Base CVSS 4.0 score
9.3CriticalVector: 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
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- Added to KEVCISA-ADP
CISA Known Exploited Vulnerabilities metadata lists this CVE as known exploited.
- ADP timelineCISA-ADP
CVE-2025-5777 added to CISA KEV
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2025-07-10T00:00:00.000Z: CVE-2025-5777 added to CISA KEV
Source materials
- CVE List V5 sourceCVE List V5
- https://support.citrix.com/support-home/kbsearch/article?articleNumber=CTX693420CVE reference, Citrix
- https://doublepulsar.com/citrixbleed-2-exploitation-started-mid-june-how-to-spot-it-f3106392aa71CVE reference, CISA-ADP · third-party-advisory, technical-description
- https://reliaquest.com/blog/threat-spotlight-citrix-bleed-2-vulnerability-in-netscaler-adc-gateway-devices/CVE reference, CISA-ADP · media-coverage
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2025-5777CVE reference, CISA-ADP · government-resource
- https://www.bleepingcomputer.com/news/security/cisa-tags-citrix-bleed-2-as-exploited-gives-agencies-a-day-to-patch/CVE reference, CVE
- https://labs.watchtowr.com/how-much-more-must-we-bleed-citrix-netscaler-memory-disclosure-citrixbleed-2-cve-2025-5777/CVE reference, CVE
- https://www.theregister.com/2025/07/10/cisa_citrixbleed_kev/CVE reference, CVE
- https://horizon3.ai/attack-research/attack-blogs/cve-2025-5777-citrixbleed-2-write-up-maybe/CVE reference, CVE
- https://www.netscaler.com/blog/news/netscaler-critical-security-updates-for-cve-2025-6543-and-cve-2025-5777/CVE reference, CVE
- https://citrixbleed.com/CVE reference, CVE
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Out-of-bounds Read
Out-of-bounds Read represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Use of Uninitialized Variable
Use of Uninitialized Variable represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.