CVE-2026-20056VulnerabilityPublished 4 Feb 2026

CVE-2026-20056: Cisco Secure Web Appliance · Download of Code Without Integrity Check

Affects Cisco Secure Web ApplianceSource CVE Database V5

Not known to be exploited · CVSS 4.0 Medium.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

4.0Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: High
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: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
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 4 Feb 2026
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 2026-10-26.

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
CiscoCisco Secure Web Appliance	Affected =11.8.0-453 =12.5.3-002 =12.0.3-007 =12.0.3-005 =14.1.0-032 =14.1.0-047 =14.1.0-041 =12.0.4-002 =14.0.2-012 =11.8.0-414 =12.0.1-268 =11.8.1-023 =11.8.3-021 =11.8.3-018 =12.5.1-011 =11.8.4-004 =12.5.2-007 =12.5.2-011 =14.5.0-498 =12.5.4-005 =12.5.4-011 =12.0.5-011 =14.0.3-014 =12.5.5-004 =12.5.5-005 =12.5.5-008 =14.0.4-005 =14.5.1-008 =14.5.1-016 =15.0.0-355 =15.0.0-322 =12.5.6-008 =15.1.0-287 =14.5.2-011 =15.2.0-116 =14.0.5-007 =15.2.0-164 =14.5.1-510 =12.0.2-012 =12.0.2-004 =14.5.1-607 =14.5.3-033 =15.0.1-004 =15.2.1-011 =14.5.0-673 =14.5.0-537 =12.0.1-334 =14.0.1-503 =14.0.1-053 =11.8.0-429 =14.0.1-040 =14.0.1-014 =12.5.1-043 =15.2.2-009 =15.5.0-566 =15.2.3-007 =15.5.0-574 =15.5.0-710 =15.2.4-022 =15.5.1-002	Fixed in–

AI-suggested

1. Monitor Cisco's official security advisories and promptly apply patches or updates once released for the affected Cisco Secure Web Appliance versions. 2. Implement strict web content filtering policies to restrict archive file downloads from untrusted or unknown sources. 3. Deploy endpoint protection solutions capable of detecting and blocking malicious archive files and payloads, adding a layer of defense beyond the web appliance. 4. Educate end users on the risks of extracting and executing files from archive downloads, emphasizing caution with unexpected or suspicious files. 5. Utilize network-based intrusion detection/prevention systems (IDS/IPS) to identify anomalous archive file traffic patterns. 6. Consider segmenting user networks to limit potential malware spread if an endpoint is compromised. 7. Enable logging and monitoring on Cisco Secure Web Appliance to detect unusual archive file activity or bypass attempts. 8. Conduct regular security assessments and penetration testing to validate the effectiveness of controls against archive-based malware delivery. 9. Employ sandboxing or detonation chambers for suspicious archive files before allowing them to reach end users. 10. Review and tighten anti-malware scanning configurations on the appliance to ensure maximum detection capabilities.

Description

A vulnerability in the Dynamic Vectoring and Streaming (DVS) Engine implementation of Cisco AsyncOS Software for Cisco Secure Web Appliance could allow an unauthenticated, remote attacker to bypass the anti-malware scanner, allowing malicious archive files to be downloaded. This vulnerability is due to improper handling of certain archive files. An attacker could exploit this vulnerability by sending a crafted archive file, which should be blocked, through an affected device. A successful exploit could allow the attacker to bypass the anti-malware scanner and download malware onto an end user workstation. The downloaded malware will not automatically execute unless the end user extracts and launches the malicious file. 

Impact

For European organizations, the primary impact of CVE-2026-20056 is the potential for malware to bypass web security defenses provided by Cisco Secure Web Appliance, a widely deployed web security gateway in enterprise environments. Successful exploitation could lead to malware delivery to end user devices, increasing the risk of endpoint compromise, data theft, or lateral movement within corporate networks. Although the malware does not execute automatically, social engineering or user error could trigger execution, amplifying risk. The vulnerability could undermine trust in web filtering and anti-malware controls, leading to increased incident response costs and potential regulatory scrutiny under GDPR if personal data is compromised. Organizations in sectors with high reliance on Cisco Secure Web Appliance for web security—such as finance, government, healthcare, and critical infrastructure—may face elevated risk. The medium severity rating reflects that exploitation requires crafted archive files and user interaction, limiting immediate impact but not eliminating risk. The lack of known exploits in the wild reduces urgency but does not preclude future attacks. Overall, the vulnerability could facilitate targeted malware campaigns against European enterprises, especially those with large distributed workforces accessing the internet through Cisco Secure Web Appliance.

References

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-wsa-archive-bypass-Scx2e8zF (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Feb 2026, 16:46 UTC

Technical details

References

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