CVE-2025-7775
CVE-2025-7775 is a security flaw in Citrix NetScaler, the gateway companies use to let staff reach internal apps from outside. Attackers can run their own code on Citrix NetScaler. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 26 Aug 2025.[1]
Citrix NetScaler is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Fixed in version 47.48, 59.22, 37.241 and 55.330.
Description
CISA calls it a memory overflow in Citrix NetScaler. In its words: “Citrix NetScaler ADC and NetScaler Gateway contain a memory overflow vulnerability that could allow for remote code execution and/or denial of service.”[1]
The CVE record adds: “Memory overflow vulnerability leading to Remote Code Execution and/or Denial of Service in NetScaler ADC and NetScaler Gateway when NetScaler is configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server (OR) NetScaler ADC and NetScaler Gateway 13.1, 14.1, 13.1-FIPS and NDcPP: LB virtual servers of type (HTTP, SSL or HTTP_QUIC) bound with IPv6 services or servicegroups bound with IPv6 servers (OR) NetScaler ADC and NetScaler Gateway 13.1, 14.1, 13.1-FIPS and NDcPP: LB virtual servers of type (HTTP, SSL or HTTP_QUIC) bound with DBS IPv6 services or servicegroups bound with IPv6 DBS servers (OR) CR virtual server with type HDX”[2]
The underlying weakness is memory buffer error (CWE-119), in MITRE’s list of common software weaknesses.
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| ADC | 47.48 |
| ADC | 59.22 |
| ADC | 37.241 |
| ADC | 55.330 |
| Gateway | 47.48 |
| Gateway | 59.22 |
| Gateway | 37.241 |
| Gateway | 55.330 |
Most families won’t have Citrix NetScaler; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 26 Aug 2025, within a day of it being made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 28 Aug 2025 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 21%. That’s in the top 3% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Citrix has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]
- Check whether you use it.Citrix NetScaler is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed (fixed in version 47.48, 59.22, 37.241 and 55.330), or not in use. CISA gave US government agencies until 28 Aug 2025 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 21%.[4] |
See also
Other Citrix NetScaler flaws
- CVE-2026-88779: improper restriction of operations within the bounds of a memory buffer ·
- CVE-2026-88772: improper restriction of operations within the bounds of a memory buffer ·
- CVE-2026-88771: improper input validation ·
- CVE-2026-19490: authentication bypass using an alternate path or channel ·
- CVE-2026-3055: out-of-bounds read ·
Other Citrix flaws
- CVE-2026-8452, Citrix NetScaler ADC and NetScaler Gateway: improper restriction of operations within the bounds of a memory buffer ·
- CVE-2024-8069, Citrix Session Recording: deserialization of untrusted data ·
- CVE-2024-8068, Citrix Session Recording: improper privilege management ·
- CVE-2025-5777, Citrix NetScaler ADC and Gateway: out-of-bounds read ·
- CVE-2025-6543, Citrix NetScaler ADC and Gateway: buffer overflow ·
Other memory buffer error flaws
- CVE-2009-3459, Adobe Acrobat and Reader: heap-based buffer overflow ·
- CVE-2025-31277, Apple devices: buffer overflow ·
- CVE-2026-3910, Chrome and other Chromium browsers: improper restriction of operations within the bounds of a memory buffer ·
- CVE-2008-0015, Microsoft Windows: video activeX control remote code execution ·
- CVE-2026-20700, Apple devices: multiple buffer overflow ·
Every Citrix flaw on CISA’s list · Everything added in August 2025
References
- ^ Cybersecurity and Infrastructure Security Agency. “Citrix NetScaler Memory Overflow Vulnerability”. Known Exploited Vulnerabilities Catalog, added 26 Aug 2025.
- ^ National Institute of Standards and Technology. “CVE-2025-7775 Detail”. National Vulnerability Database, published 26 Aug 2025.
- ^ Citrix. Advisories and fixes: support.citrix.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.207, percentile 97.5, 31 Oct 2026.
- CVE Program. “CVE-2025-7775”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.