CVE-2026-8452
CVE-2026-8452 is a security flaw in Citrix NetScaler ADC and NetScaler Gateway, the gateway companies use to let staff reach internal apps from outside. Attackers can crash Citrix NetScaler ADC and NetScaler Gateway or stop it working. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 26 Aug 2026.[1]
Citrix NetScaler ADC and NetScaler Gateway 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 72.61, 63.18 and 37.272.
Description
CISA calls it an improper restriction of operations within the bounds of a memory buffer in Citrix NetScaler ADC and NetScaler Gateway. In its words: “Citrix NetScaler ADC and NetScaler Gateway contain an improper restriction of operations within the bounds of a memory buffer vulnerability which could lead to denial of service.”[1]
The CVE record adds: “Memory overflow vulnerability NetScaler ADC and NetScaler Gateway leading to unpredictable or erroneous behavior and Denial of Service if the appliance is configured as a Gateway (SSL VPN, ICA Proxy, CVPN, RDP Proxy) or AAA virtual server”[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 | 72.61 |
| ADC | 63.18 |
| ADC | 37.272 |
| Gateway | 72.61 |
| Gateway | 63.18 |
Most families won’t have Citrix NetScaler ADC and NetScaler Gateway; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 26 Aug 2026, 57 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 29 Aug 2026 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 1%. That’s in the top 37% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
Citrix has published a fix or advice.[3] CISA’s required action: “Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes).”[1]
- Check whether you use it.Citrix NetScaler ADC and NetScaler Gateway 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 72.61, 63.18 and 37.272), or not in use. CISA gave US government agencies until 29 Aug 2026 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 1%.[4] |
See also
Other Citrix NetScaler ADC and NetScaler Gateway flaws
- CVE-2023-6549: buffer overflow ·
- CVE-2023-6548: code injection ·
- CVE-2023-4966: buffer overflow ·
- CVE-2023-3519: code injection ·
Other Citrix flaws
- CVE-2026-88779, Citrix NetScaler: improper restriction of operations within the bounds of a memory buffer ·
- CVE-2026-88772, Citrix NetScaler: improper restriction of operations within the bounds of a memory buffer ·
- CVE-2026-88771, Citrix NetScaler: improper input validation ·
- CVE-2026-19490, Citrix NetScaler: authentication bypass using an alternate path or channel ·
- CVE-2026-3055, Citrix NetScaler: out-of-bounds read ·
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 ·
Added the same day
- CVE-2022-0995, Linux Kernel: out-of-bounds write ·
- CVE-2021-23758, Ajax.NET Professional: deserialization of untrusted data ·
- CVE-2019-1068, Microsoft SQL Server: remote code execution ·
- CVE-2015-5287, Red Hat Automatic Bug Reporting Tool: privilege escalation ·
- CVE-2015-3246, Red Hat Libuser: race condition ·
Every Citrix flaw on CISA’s list · Everything added in August 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “Citrix NetScaler ADC and NetScaler Gateway Improper Restriction of Operations within the Bounds of a Memory Buffer Vulnerability”. Known Exploited Vulnerabilities Catalog, added 26 Aug 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-8452 Detail”. National Vulnerability Database, published 30 Jun 2026.
- ^ Citrix. Advisories and fixes: support.citrix.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.010, percentile 63.2, 31 Oct 2026.
- CVE Program. “CVE-2026-8452”. 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.