CVE-2022-27518
CVE-2022-27518 is a security flaw in Citrix Application Delivery Controller (ADC) and Gateway, the gateway companies use to let staff reach internal apps from outside. Attackers can run their own code on Citrix Application Delivery Controller (ADC) and Gateway from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 13 Dec 2022.[1]
Citrix Application Delivery Controller (ADC) and 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. Citrix has published a fix or advice.
Description
CISA calls it an authentication bypass in Citrix Application Delivery Controller (ADC) and Gateway. In its words: “Citrix Application Delivery Controller (ADC) and Gateway, when configured with SAML SP or IdP configuration, contain an authentication bypass vulnerability that allows an attacker to execute code as administrator.”[1]
The underlying weakness is CWE-664, in MITRE’s list of common software weaknesses.[2]
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 doesn’t list version ranges for it; Citrix’s advisory has them[3]. CISA names the product as Citrix Application Delivery Controller (ADC) and Gateway.
Most families won’t have Citrix Application Delivery Controller (ADC) and Gateway; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 13 Dec 2022, 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 3 Jan 2023 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 7%. That’s in the top 6% 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 updates per vendor instructions.”[1]
- Check whether you use it.Citrix Application Delivery Controller (ADC) and 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, or not in use. CISA gave US government agencies until 3 Jan 2023 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 7%.[4] |
See also
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-2026-8452, Citrix NetScaler ADC and NetScaler Gateway: improper restriction of operations within the bounds of a memory buffer ·
Added the same day
- CVE-2022-44698, Microsoft Defender: smartScreen security feature bypass ·
- CVE-2022-42475, Fortinet FortiOS: heap-based buffer overflow ·
- CVE-2022-26501, Veeam Backup & Replication: remote code execution ·
- CVE-2022-26500, Veeam Backup & Replication: remote code execution ·
Every Citrix flaw on CISA’s list · Everything added in December 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “Citrix Application Delivery Controller (ADC) and Gateway Authentication Bypass Vulnerability”. Known Exploited Vulnerabilities Catalog, added 13 Dec 2022.
- ^ National Institute of Standards and Technology. “CVE-2022-27518 Detail”. National Vulnerability Database, published 13 Dec 2022.
- ^ Citrix. Advisories and fixes: citrix.com, support.citrix.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.069, percentile 94.0, 31 Oct 2026.
- CVE Program. “CVE-2022-27518”. 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.