CVE-2020-3433
CVE-2020-3433 is a security flaw in Cisco AnyConnect Secure, Cisco’s business networking equipment. Someone who already has a way in can use Cisco AnyConnect Secure to run their own code. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 24 Oct 2022, and says ransomware gangs have used it.[1]
Cisco AnyConnect Secure 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. Cisco has published a fix or advice.
Description
CISA calls it a mobility client for windows DLL hijacking in Cisco AnyConnect Secure. In its words: “Cisco AnyConnect Secure Mobility Client for Windows interprocess communication (IPC) channel allows for insufficient validation of resources that are loaded by the application at run time. An attacker with valid credentials on Windows could execute code on the affected machine with SYSTEM privileges.”[1]
The CVE record adds: “A vulnerability in the interprocess communication (IPC) channel of Cisco AnyConnect Secure Mobility Client for Windows could allow an authenticated, local attacker to perform a DLL hijacking attack. To exploit this vulnerability, the attacker would need to have valid credentials on the Windows system. The vulnerability is due to insufficient validation of resources that are loaded by the application at run time. An attacker could exploit this vulnerability by sending a crafted IPC message to the AnyConnect process. A successful exploit could allow the attacker to execute arbitrary code on the affected machine with SYSTEM privileges. To exploit this vulnerability, the attacker would need to have valid credentials on the Windows system.”[2]
The underlying weakness is CWE-427, in MITRE’s list of common software weaknesses.
It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Cisco’s advisory has them[3]. CISA names the product as Cisco AnyConnect Secure.
Most families won’t have Cisco AnyConnect Secure; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 24 Oct 2022, 798 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 14 Nov 2022 to fix it.[1] CISA says ransomware gangs have used it.
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 10%. That’s in the top 5% 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
Cisco has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.Cisco AnyConnect Secure 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 14 Nov 2022 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 7.8.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks, noting that ransomware gangs have used it.[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 10%.[4] |
See also
Other Cisco AnyConnect Secure flaws
- CVE-2020-3153: mobility client for windows uncontrolled search path ·
Other Cisco flaws
- CVE-2026-76418, Cisco Secure Firewall ASA Software and Cisco Secure FTD Software: unchecked return value to NULL pointer dereference ·
- CVE-2026-76519, Cisco Secure Email Gateway: relative path traversal ·
- CVE-2026-76504, Cisco Catalyst SD-WAN Manager: hex encoding ·
- CVE-2026-76460, Cisco Identity Services Engine: incorrect use of privileged APIs ·
- CVE-2026-76461, Cisco Secure Email Gateway: SQL injection ·
Similar flaws
- CVE-2026-110936, Siemens Software Center: uncontrolled search path element ·
Added the same day
- CVE-2020-3153, Cisco AnyConnect Secure: mobility client for windows uncontrolled search path ·
- CVE-2018-19323, GIGABYTE products: privilege escalation ·
- CVE-2018-19322, GIGABYTE products: code execution ·
- CVE-2018-19321, GIGABYTE products: privilege escalation ·
- CVE-2018-19320, GIGABYTE products: unspecified ·
Every Cisco flaw on CISA’s list · Everything added in October 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “Cisco AnyConnect Secure Mobility Client for Windows DLL Hijacking Vulnerability”. Known Exploited Vulnerabilities Catalog, added 24 Oct 2022.
- ^ National Institute of Standards and Technology. “CVE-2020-3433 Detail”. National Vulnerability Database, published 17 Aug 2020.
- ^ Cisco. Advisories and fixes: tools.cisco.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.100, percentile 95.6, 31 Oct 2026.
- CVE Program. “CVE-2020-3433”. 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.