What is CVE-2026-20122?

CVE-2026-20122 is Cisco Catalyst SD-WAN Manager Arbitrary File Overwrite Vulnerability. The supplied enrichment data classifies it as Remote Code Exec mapped to CWE-648 CWE-648.

Which versions are affected?

Affected product and version evidence is listed in the product table above. Current public advisories should be checked for exact version scope before patch targeting is finalized.

Is there active exploitation?

Yes: CISA KEV signal present. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

Is there a public exploit?

11 public PoC repositories reported; 2 marked weaponized in current dataset. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with web/proxy/WAF logs, application logs, network IDS/IPS, EDR process telemetry, host service logs where available. Look for vulnerability-class behavior, product errors, suspicious authentication events, exploit probes, and abnormal process activity based only on evidence that applies to the affected product.

How should teams prioritize it?

Prioritize CVE-2026-20122 using CVSS 5.4, EPSS 25%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

The supplied mitigation guidance says to apply vendor patches and restrict external exposure until fixed. Fixed-version evidence is listed in the mitigation section above.

Which threat actors are linked publicly?

No public threat actor linkage is confirmed from current sources. Do not attribute exploitation to a threat actor unless the source evidence explicitly supports that linkage.

What should be done in the next 24 hours?

Identify exposed assets running affected vendor/product/version combinations. Treat as emergency remediation because CISA KEV status is present. Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class. Open remediation tickets with affected assets, owners, evidence status, and detection coverage so decisions are traceable.

CISA KEVmediumRemote Code Execpublic exploit

CVE-2026-20122

Cisco Catalyst SD-WAN Manager Arbitrary File Overwrite Vulnerability

Q: Is it in CISA KEV?

Yes. The supplied enrichment data lists CVE-2026-20122 in CISA KEV with 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). Adhere to the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.. KEV status should be monitored because it can change after initial disclosure or after exploitation becomes publicly confirmed.

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.

Published Feb 25, 2026Updated Jun 17, 2026Sources: NVD, Cisco (CNA), CISA, FIRST EPSS, GitHub, GitHub Security Advisory

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Confirmed

CISA KEV, listed Apr 20, 2026

EPSS

25%

ahead of 98% of scored CVEs

Affects

Cisco

335 products listed

CVSS base

5.4

medium

CISA SSVC assessment

Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.

CISA

Exploitation

Active

none · proof-of-concept · active

Automatable

can an attacker script all four kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

The vendor's own words where we have them.

Upgrade Cisco Catalyst SD-WAN Manager to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.

CISA 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). Adhere to the applicable BOD 22-01 guidance for cloud services or discontinue use of the product if mitigations are not available.

Federal deadline Apr 23, 2026 — passed 122 days ago

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

Identify exposed assets running affected vendor/product/version combinations.
Treat as emergency remediation because CISA KEV status is present.
Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

Vendor	Product	Versions	Status
Cisco	Cisco Catalyst SD-WAN Manager	20.1.12	Vulnerable
Cisco	Cisco Catalyst SD-WAN Manager	19.2.1	Vulnerable
Cisco	Cisco Catalyst SD-WAN Manager	18.4.4	Vulnerable
Cisco	Cisco Catalyst SD-WAN Manager	18.4.5	Vulnerable
Cisco	Cisco Catalyst SD-WAN Manager	20.1.1.1	Vulnerable
Cisco	Cisco Catalyst SD-WAN Manager	20.1.1	Vulnerable
Cisco	Cisco Catalyst SD-WAN Manager	19.3.0	Vulnerable
Cisco	Cisco Catalyst SD-WAN Manager	19.2.2	Vulnerable
Cisco	Cisco Catalyst SD-WAN Manager	19.2.099	Vulnerable
Cisco	Cisco Catalyst SD-WAN Manager	18.3.6	Vulnerable
Cisco	Cisco Catalyst SD-WAN Manager	18.3.7	Vulnerable
Cisco	Cisco Catalyst SD-WAN Manager	19.2.0	Vulnerable

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Availability

None

Confidentiality

Low

Integrity

Low

Scope

Unchanged

Attack Complexity

Low

Attack Vector

Network

Privileges Req

Low

User Interaction

None

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Source
5.4	CVSS 3.1	medium	2.8	2.5	Cisco (CNA), NVD, GHSA

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

Weakness & attack patterns

CWE-648

Inferred from the weakness class — not observed against this CVE.

CAPEC-242 · Code InjectionCAPEC-35 · Leverage Executable Code in Non-Executable Files

CISA KEV details

CISA lists a CVE here once it has evidence of exploitation against real targets.

CISAThat month →

Listed

Apr 20, 2026

Federal deadline

Apr 23, 2026

passed 122 days ago

Ransomware use

Unknown

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a date to argue against.

Public exploit

Capability, not use: code existing is a different claim from anyone running it.

Repositories

2 of the 5 sampled are weaponized

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

Prioritize edge telemetry for network-reachable Cisco Catalyst SD-WAN Manager.
Monitor for scanner or exploit-pattern traffic after 11 public PoC repositories were reported.

web/proxy/WAF logsapplication logsnetwork IDS/IPSEDR process telemetryhost service logs

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

2026
Added · CVSS 3.1 5.4 (AV:N)
Jun 17, 2026 · NVD
Added to CISA KEV catalog
Apr 20, 2026 · CISA
Initial · CVE published
Feb 25, 2026 · NVD
Added · GHSA-9qpv-49q8-9chx published (medium)
Feb 25, 2026 · GitHub Security Advisory

References

6 on the record

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-authbp-qwCX8D4v
Vendor Advisory
www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-20122
US Government Resource
nvd.nist.gov/vuln/detail/CVE-2026-20122
NVD, Vendor Advisory
github.com/advisories/GHSA-9qpv-49q8-9chx
Exploit, Third Party Advisory
www.cisa.gov/news-events/directives/ed-26-03-mitigate-vulnerabilities-cisco-sd-wan-systems
US Government Resource
www.cisa.gov/news-events/directives/supplemental-direction-ed-26-03-hunt-and-hardening-guidance-cisco-sd-wan-systems
US Government Resource

Elsewhere on this site

Ciscoevery CVE for this vendor
April 2026what else CISA listed
Remote Code Execsame class
CWE-648other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record1

What should defenders know first?

CVE-2026-20122 is Cisco Catalyst SD-WAN Manager Arbitrary File Overwrite Vulnerability, a medium vulnerability affecting Cisco Catalyst SD-WAN Manager from Cisco. The current evidence lists it in CISA KEV, and the exploit status is: Yes: CISA KEV signal present. Public exploit evidence is: 11 public PoC repositories reported; 2 marked weaponized in current dataset. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 5.4 describes technical severity, while EPSS 25% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.