CVE-2025-20339VulnerabilityPublished 24 Sep 2025

CVE-2025-20339: Cisco SD-WAN vEdge Cloud · Improper Access Control

Affects Cisco SD-WAN vEdge CloudSource CVE Database V5

Not known to be exploited · CVSS 5.8 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

5.8Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.3% chance of exploitation in 30 days – higher than 24% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Changed
Confidentiality: None
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 24 Sep 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Cisco Cisco SD-WAN vEdge Cloud	Affected =20.9.1 =20.9.1.1 =20.9.2 =20.9.3 =20.9.3.1 =20.9.2.2 =20.9.2.3 =20.9.4 =20.9.5 =20.9.5.1 =20.9.6 =20.9.5.3	Fixed in–

AI-suggested

European organizations should immediately inventory their Cisco SD-WAN vEdge Cloud deployments to identify affected versions (20.9.1 through 20.9.6 and minor revisions). Until an official patch is released by Cisco, organizations should implement compensating controls such as: 1) Tightening network segmentation to limit exposure of SD-WAN devices to untrusted networks, 2) Applying strict ingress and egress filtering on upstream routers and firewalls to block unauthorized IPv4 traffic targeting SD-WAN interfaces, 3) Monitoring network traffic for anomalous or unauthorized packets that could indicate ACL bypass attempts, 4) Employing intrusion detection/prevention systems (IDS/IPS) with updated signatures to detect suspicious activity related to ACL bypass, 5) Restricting management access to SD-WAN devices to trusted administrative networks only, and 6) Preparing for rapid deployment of Cisco patches once available by establishing a vulnerability management process that prioritizes this issue. Additionally, organizations should review and harden ACL configurations to minimize reliance on implicit deny rules and consider explicit deny statements where feasible. Regular security audits and penetration testing focusing on SD-WAN infrastructure can help detect exploitation attempts early.

Description

A vulnerability in the access control list (ACL) processing of IPv4 packets of Cisco SD-WAN vEdge Software could allow an unauthenticated, remote attacker to bypass a configured ACL. This vulnerability is due to the improper enforcement of the implicit deny all at the end of a configured ACL. An attacker could exploit this vulnerability by attempting to send unauthorized traffic to an interface on an affected device. A successful exploit could allow the attacker to bypass an ACL on the affected device.

Impact

For European organizations, this vulnerability poses a significant risk to network security, especially for enterprises and service providers relying on Cisco SD-WAN vEdge Cloud for secure WAN connectivity. By bypassing ACLs, attackers can potentially inject unauthorized traffic into protected network segments, leading to unauthorized access, lateral movement, or data integrity compromise. Although confidentiality and availability impacts are not directly indicated, the integrity impact could allow attackers to manipulate or inject malicious traffic, undermining trust in network communications. This could facilitate further attacks such as man-in-the-middle, data tampering, or evasion of network-based security controls. Given the widespread adoption of Cisco SD-WAN solutions in Europe for critical infrastructure, finance, telecommunications, and government networks, exploitation could disrupt secure communications and expose sensitive internal resources. The lack of authentication and user interaction requirements lowers the barrier for exploitation, increasing the threat level. However, the absence of known exploits in the wild and the medium severity rating suggest that immediate widespread exploitation is not yet observed, but organizations should proactively address the vulnerability to prevent future attacks.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-defaultacl-pSJk9nVF (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 24 Sep 2025, 16:48 UTC

Technical details

References

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