A vulnerability in the Multipurpose Internet Mail Extensions (MIME) scanner of Cisco AsyncOS Software for Cisco Email Security Appliances (E
A vulnerability in the Multipurpose Internet Mail Extensions (MIME) scanner of Cisco AsyncOS Software for Cisco Email Security Appliances (ESA) could allow an unauthenticated, remote attacker to bypass configured user filters on the device. The vulnerability is due to improper error handling of a malformed MIME header in an email attachment. An attacker could exploit this vulnerability by sending an email with a crafted MIME attachment. For example, a successful exploit could allow the attacker to bypass configured user filters to drop the email. The malformed MIME headers may not be RFC compliant. However, some mail clients could still allow users to access the attachment, which may not have been properly filtered by the device. Cisco Bug IDs: CSCvf44666.
- Published
- Nov 30, 2017
- Updated
- Jun 16, 2026
- EPSS
- 1.6% · 76th percentile
- CWE
- CWE-254
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Report tools
Action score
23
Monitor
Low priority for now.
- CVSS
- 23 / 40 · 5.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.6%
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
| Vendor | Product | CPE |
|---|---|---|
| cisco | asyncos | cpe:2.3:o:cisco:asyncos |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- cisco asyncosall versions
Versions reported by the vendor
Affected version ranges reported by the assigning authority (cisco). Independent of NVD's CPE analysis and usually ahead of it.
n/a Cisco Email Security Appliance
- Cisco Email Security Applianceaffected
Same product
cisco: all recordsOther highest-scoring records for the same primary product.
- CVE-2025-20393Cisco Secure Email Gateway and Cisco Secure Email and Web Manager Remote Command Execution VulnerabilityKEV80Now
- CVE-2026-76461Cisco Secure Email Gateway SQL Injection VulnerabilityKEV77This week
- CVE-2022-20871Cisco Secure Web Appliance Privilege Escalation Vulnerability36Monitor
- CVE-2022-20868A vulnerability in the web-based management interface of Cisco Email Security Appliance, Cisco Secure Email and Web Manager and Cisco Secure35Monitor
- CVE-2019-15956Cisco Web Security Appliance Unauthorized Device Reset Vulnerability35Monitor
- CVE-2018-15460Cisco Email Security Appliance URL Filtering Denial of Service Vulnerability35Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- low · data or configuration can be modified
- Availability
- none
Impact can extend beyond the vulnerable component (scope changes).
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality impact
- None
- Integrity impact
- Low
- Availability impact
- None
Weakness class (CWE)
CWE-254 · 7PK - Security FeaturesCVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
- www.securityfocus.com/bid/102002
- www.securitytracker.com/id/1039917
- tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20171129-esa
Vendor advisories and official records. Exploit/PoC links are deliberately left out.