Unauthenticated ACL bypass via unenforced implicit deny
Published Sep 24, 2025 · Updated Sep 24, 2025
Improper access control in Cisco SD-WAN vEdge Software allows remote attackers to bypass configured IPv4 ACLs on affected routers. IPv4 ACL processing fails to enforce the implicit deny-all rule at the end of a configured ACL, so unauthorized packets reach the protected interface. No authentication or special configuration is required; exposure and downstream impact depend on the assets and services that the ACL protects.
Summary
What happened
Improper access control in Cisco SD-WAN vEdge Software allows remote attackers to bypass configured IPv4 ACLs on affected routers. IPv4 ACL processing fails to enforce the implicit deny-all rule at the end of a configured ACL, so unauthorized packets reach the protected interface. No authentication or special configuration is required; exposure and downstream impact depend on the assets and services that the ACL protects.
The record
- CVE
- CVE-2025-20339
- Published
- Sep 24, 2025
- Updated
- Sep 24, 2025
- Vendor
- ClamAV
- Product
- Cisco SD-WAN vEdge Router
- Classifications
- CWE-284
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 24, 2025CVE publishedPublication date reported by the CVE source.
- Sep 24, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=20.12.1
- Affected versionversion=20.12.3.1
- Affected versionversion=20.3.1
- Affected versionversion=20.3.2
- Affected versionversion=20.3.3
- Affected versionversion=20.3.3.2
- Affected versionversion=20.3.4
- Affected versionversion=20.3.4.3
- Affected versionversion=20.3.5
- Affected versionversion=20.3.5.1
- Affected versionversion=20.3.6
- Affected versionversion=20.3.7
- Affected versionversion=20.3.7.1
- Affected versionversion=20.3.7.2
- Affected versionversion=20.3.8
- Affected versionversion=20.4.1
- Affected versionversion=20.4.1.1
- Affected versionversion=20.4.1.2
- Affected versionversion=20.4.2
- Affected versionversion=20.4.2.3
- Affected versionversion=20.9.1
- Affected versionversion=20.9.2
- Affected versionversion=20.9.2.2
- Affected versionversion=20.9.2.3
- Affected versionversion=20.9.3
- Affected versionversion=20.9.3.1
- Affected versionversion=20.9.4
- Affected versionversion=20.9.4.1777
- Affected versionversion=20.9.5
- Affected versionversion=20.9.5.1
- Affected versionversion=20.9.5.3
- Affected versionversion=20.9.6
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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