CVE-2026-20122
CVE-2026-20122 is a security flaw in Cisco Catalyst SD-WAN Manger, Cisco’s business networking equipment. Attackers can reach parts of Cisco Catalyst SD-WAN Manger that should be locked to them. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 20 Apr 2026.[1]
Cisco Catalyst SD-WAN Manger 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 catalyst SD-WAN manager incorrect use of privileged APIs in Cisco Catalyst SD-WAN Manger. In its words: “Cisco Catalyst SD-WAN Manager contains an incorrect use of privileged APIs vulnerability due to improper file handling on the API interface of an affected system. An attacker could exploit this vulnerability by uploading a malicious file on the local file system. A successful exploit could allow the attacker to overwrite arbitrary files on the affected system and gain vmanage user privileges.”[1]
The CVE record adds: “A vulnerability in the API of Cisco Catalyst SD-WAN Manager could allow an authenticated, remote attacker to overwrite arbitrary files on the local file system. To exploit this vulnerability, the attacker must have valid read-only credentials with API access on the affected system. This vulnerability is due to improper file handling on the API interface of an affected system. An attacker could exploit this vulnerability by uploading a malicious file on the local file system. A successful exploit could allow the attacker to overwrite arbitrary files on the affected system and gain vmanage user privileges.”[2]
The underlying weakness is CWE-648, in MITRE’s list of common software weaknesses.
It scores 5.4 out of 10 on the Common Vulnerability Scoring System, which rates it medium, 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 Catalyst SD-WAN Manger.
Most families won’t have Cisco Catalyst SD-WAN Manger; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 20 Apr 2026, 54 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 23 Apr 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 26%. 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
Cisco has published a fix or advice.[3] CISA’s required action: “Please adhere to CISA’s guidelines to assess exposure and mitigate risks associated with Cisco SD-WAN devices as outlines in CISA’s Emergency Directive 26-03 (URL listed below in Notes) and CISA’s “Hunt & Hardening Guidance for Cisco SD-WAN Devices (URL listed below in Notes).”[1]
- Check whether you use it.Cisco Catalyst SD-WAN Manger 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 23 Apr 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 5.4.[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 26%.[4] |
See also
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 ·
Added the same day
- CVE-2026-20133, Cisco Catalyst SD-WAN Manager: exposure of sensitive information to an unauthorized actor ·
- CVE-2026-20128, Cisco Catalyst SD-WAN Manager: storing passwords in a recoverable format ·
- CVE-2025-48700, Synacor Zimbra Collaboration Suite (ZCS): cross-site scripting ·
- CVE-2025-32975, Quest KACE Systems Management Appliance (SMA): improper authentication ·
- CVE-2025-2749, Kentico Xperience: xperience path traversal ·
Every Cisco flaw on CISA’s list · Everything added in April 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “Cisco Catalyst SD-WAN Manager Incorrect Use of Privileged APIs Vulnerability”. Known Exploited Vulnerabilities Catalog, added 20 Apr 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-20122 Detail”. National Vulnerability Database, published 25 Feb 2026.
- ^ Cisco. Advisories and fixes: sec.cloudapps.cisco.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.258, percentile 98.0, 31 Oct 2026.
- CVE Program. “CVE-2026-20122”. 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.