CVE-2025-5777 — Citrix NetScaler ADC and Gateway Out-of-Bounds Read Vulnerability

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

CISA required action CISA

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

US federal deadline: Jul 11, 2025 — passed 461 day(s) ago

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

1. Identify exposed assets running the affected vendor/product/version combinations (Citrix Netscaler Application Delivery Controller, Citrix Netscaler Gateway, NetScaler ADC…).
2. Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
3. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
4. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
5. EPSS ahead of 100% of scored CVEs: prioritize it in the patch queue.
6. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-908 · Use of Uninitialized Resource

Other CVEs with this weakness →

CISA KEV details CISA

CISA lists a CVE once it has evidence of exploitation against real targets.

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.

Public exploits, PoCs and detection templates

Public code that demonstrates or tests the flaw raises the odds of mass exploitation — and Nuclei templates help find vulnerable assets in your environment.

Warning: public PoCs are sometimes disguised malware. Use them only for authorized testing in an isolated environment. This portal does not host exploit code — it only points to the sources.

EPSS over time FIRST

Oct 12, 2026 → Oct 14, 2026 · 3 reading(s) · max 99.97%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

• Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
• Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
• Hunt retroactively in logs from before Jul 10, 2025 (KEV listing): exploitation may have started earlier.

Timeline

What happened to this CVE, newest first.

• 2026
• Affected products added · netscaler/adc, netscaler/gateway
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• SSVC assessment updated
  Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
• Record published
  Oct 13, 2026
• Affected products added · citrix/netscaler application delivery controller, citrix/netscaler gateway
  Oct 13, 2026 · NIST National Vulnerability Database
• CVSS changed · 7.5
  Oct 13, 2026 · NIST National Vulnerability Database
• Source status changed · → Analyzed
  Oct 13, 2026 · NIST National Vulnerability Database
• Added to CISA KEV (detected)
  Oct 13, 2026 · CISA Known Exploited Vulnerabilities
• Record created in this database
  Oct 13, 2026 · CISA Known Exploited Vulnerabilities
• 2025
• Added to CISA KEV catalog
  Jul 9, 2025 · CISA
• CVE published
  Jun 17, 2025 · Citrix

Source activity

Repeated readings are counted rather than listed.

• 2× References added · Oct 13, 2026 – Oct 13, 2026
• 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

18 on the record

• support.citrix.com/support-home/kbsearch/article
  Vendor Advisory, NIST National Vulnerability Database
• www.cisa.gov/known-exploited-vulnerabilities-catalog
  US Government Resource, NIST National Vulnerability Database
• horizon3.ai/attack-research/attack-blogs/cve-2025-5777-citrixbleed-2-write-up-may
  Third Party Advisory, NIST National Vulnerability Database
• www.netscaler.com/blog/news/netscaler-critical-security-updates-for-cve-2025-6543-and-c
  Third Party Advisory, NIST National Vulnerability Database
• doublepulsar.com/citrixbleed-2-exploitation-started-mid-june-how-to-spot-it-f3106392aa
  Third Party Advisory, NIST National Vulnerability Database
• nvd.nist.gov/vuln/detail/CVE-2025-5777
  GitHub Security Advisories
• www.theregister.com/2025/07/10/cisa_citrixbleed_kev/
  Press/Media Coverage, NIST National Vulnerability Database
• www.bleepingcomputer.com/news/security/cisa-tags-citrix-bleed-2-as-exploited-gives-agencies-a-
  GitHub Security Advisories
• horizon3.ai/attack-research/attack-blogs/cve-2025-5777-citrixbleed-2-write-up-may
  GitHub Security Advisories
• labs.watchtowr.com/how-much-more-must-we-bleed-citrix-netscaler-memory-disclosure-citrix
  Third Party Advisory, NIST National Vulnerability Database
• reliaquest.com/blog/threat-spotlight-citrix-bleed-2-vulnerability-in-netscaler-adc-g
  GitHub Security Advisories
• citrixbleed.com
  Broken Link, Third Party Advisory, NIST National Vulnerability Database
• www.theregister.com/2025/07/10/cisa_citrixbleed_kev
  GitHub Security Advisories
• github.com/advisories/GHSA-29vj-j5w5-pcph
  GitHub Security Advisories
• reliaquest.com/blog/threat-spotlight-citrix-bleed-2-vulnerability-in-netscaler-adc-g
  Third Party Advisory, NIST National Vulnerability Database
• www.netscaler.com/blog/news/netscaler-critical-security-updates-for-cve-2025-6543-and-c
  GitHub Security Advisories
• www.bleepingcomputer.com/news/security/cisa-tags-citrix-bleed-2-as-exploited-gives-agencies-a-
  Press/Media Coverage, Third Party Advisory, NIST National Vulnerability Database
• labs.watchtowr.com/how-much-more-must-we-bleed-citrix-netscaler-memory-disclosure-citrix
  GitHub Security Advisories

Elsewhere on this site

Related CVEs (same products)

• Critical CVE-2026-107406 Memory overflow vulnerability leading to Remote Code Execution or Denial of Service 7d
• High CVE-2026-88779 Citrix NetScaler Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability KEV 11d
• High CVE-2026-88778 Predictable exact value from previous values vulnerability in Citrix NetScaler ADC and… 18d
• Critical CVE-2026-88776 Buffer Errors (Improper Restriction of Operations within Memory Bounds) in Citrix Netscaler Application Delivery Controller 18d
• Critical CVE-2026-88777 Buffer Errors (Improper Restriction of Operations within Memory Bounds) in Citrix Netscaler Application Delivery Controller 18d
• High CVE-2026-88774 Improper Input Validation in Citrix Netscaler Application Delivery Controller 18d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

• No fixed version, patch or mitigation documented.
• No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
• No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
• No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2025-5777 is "Citrix NetScaler ADC and Gateway Out-of-Bounds Read Vulnerability", rated High. It affects Netscaler Application Delivery Controller (Citrix); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 7.5 describes technical severity. EPSS 99.97% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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