Security readout for executives and security teams
Plain-English summary
This flaw can let malicious files slip through HTTP file controls on affected Cisco/Snort-based inspection systems. It does not directly compromise the firewall, but it weakens a security control that may be relied on to block malware delivery.
Executive priority
Treat as a security-control bypass with moderate business urgency. Prioritize environments where Cisco/Snort inspection is a primary malware prevention layer for outbound or inbound HTTP traffic.
Technical view
The Snort HTTP detection engine mishandles modified packets in chunked HTTP responses. A remote unauthenticated attacker could send crafted HTTP traffic through an affected device and bypass a configured HTTP File Policy, enabling delivery of content that should have been blocked.
Likely exposure
Relevant exposure includes Cisco Firepower Threat Defense and other Cisco products using the affected Snort engine, plus Debian Snort packages referenced by Debian advisories. Risk depends on inline HTTP inspection and File Policy use. Exact affected versions are not provided in the prompt bundle.
Exploitation context
The CVE is not listed as KEV in the supplied bundle, and no cited source states active exploitation. The attack is network-reachable, unauthenticated, and low-complexity, but impact is limited to bypassing an HTTP file policy rather than direct system takeover.
Researcher notes
Evidence supports a CWE-693 protection-mechanism failure in Snort HTTP chunked-response handling. The bundle does not provide fixed Cisco version ranges, affected non-FTD Cisco product names, proof-of-concept status, or exploitation telemetry.
Mitigation direction
- Review Cisco advisory guidance for affected products and fixed releases.
- Apply Cisco software or rule-engine updates where applicable.
- Apply Debian Snort security updates on Debian-managed systems.
- Do not rely only on HTTP File Policy for malware blocking.
- Use layered controls for web, endpoint, and email content inspection.
Validation and detection
- Inventory Cisco FTD and Snort deployments handling HTTP traffic.
- Confirm whether HTTP File Policy is configured and enforced inline.
- Compare installed versions against Cisco and Debian advisories.
- Verify security update deployment through package or appliance management records.
- Review monitoring for unexpected malicious file delivery over HTTP.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-693: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2020-3299 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 5.8 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N3.91.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
5.8MediumVector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- 20201021 Multiple Cisco Products SNORT HTTP Detection Engine File Policy Bypass VulnerabilityCVE reference · vendor-advisory
- [debian-lts-announce] 20230210 [SECURITY] [DLA 3317-1] snort security updateCVE reference · mailing-list
- DSA-5354CVE reference · vendor-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Protection Mechanism Failure
Protection Mechanism Failure represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.