Multiple Cisco Products SNORT HTTP Detection Engine File Policy Bypass Vulnerability
Noroxi assessment
Priority: Monitor (action score 24/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 2.3% (FIRST EPSS); higher than 82.9% of all records.
- 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.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: snort (Debian:10) 2.9.20-0+deb10u1; snort (Debian:11) 2.9.20-0+deb11u1.
Low priority for now. Upgrade to snort (Debian:10) 2.9.20-0+deb10u1; snort (Debian:11) 2.9.20-0+deb11u1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Multiple Cisco products are affected by a vulnerability in the Snort detection engine that could allow an unauthenticated, remote attacker to bypass a configured File Policy for HTTP. The vulnerability is due to incorrect detection of modified HTTP packets used in chunked responses. An attacker could exploit this vulnerability by sending crafted HTTP packets through an affected device. A successful exploit could allow the attacker to bypass a configured File Policy for HTTP packets and deliver a malicious payload.
- Published
- Oct 21, 2020
- Updated
- Aug 11, 2026
- EPSS
- 2.3% · 83th percentile
- CWE
- CWE-693
Report tools
Action score
24
Monitor
Low priority for now.
- CVSS
- 23 / 40 · 5.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 2.3%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 5.8
- CNA · cisco
- 5.8
- agree
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| cisco | secure firewall threat defense | cpe:2.3:a:cisco:secure_firewall_threat_defense |
| cisco | cloud services router 1000v | cpe:2.3:a:cisco:cloud_services_router_1000v |
| cisco | isrv | cpe:2.3:a:cisco:isrv |
| cisco | 1100-4p | cpe:2.3:h:cisco:1100-4p |
| cisco | 1100-8p | cpe:2.3:h:cisco:1100-8p |
| cisco | 1101-4p | cpe:2.3:h:cisco:1101-4p |
| cisco | 1109-2p | cpe:2.3:h:cisco:1109-2p |
| cisco | 1109-4p | cpe:2.3:h:cisco:1109-4p |
| cisco | 1111x-8p | cpe:2.3:h:cisco:1111x-8p |
| cisco | 4221 integrated services router | cpe:2.3:h:cisco:4221_integrated_services_router |
| cisco | 4331 integrated services router | cpe:2.3:h:cisco:4331_integrated_services_router |
| cisco | 4431 integrated services router | cpe:2.3:h:cisco:4431_integrated_services_router |
and 4 more
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- cisco secure firewall threat defense6.0.0 and later · before 6.3.0.1
- snort snortbefore 2.9.13.1
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.
Cisco Cisco Firepower Threat Defense Software
- n/aaffected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:10 | snort | before 2.9.20-0+deb10u1 | 2.9.20-0+deb10u1 |
| Debian:11 | snort | before 2.9.20-0+deb11u1 | 2.9.20-0+deb11u1 |
Same product
cisco: all recordsOther highest-scoring records for the same primary product.
- CVE-2020-3259Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Web Services Information Disclosure VulnerabilityKEV82Now
- CVE-2020-3580Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Web Services Interface Cross-Site Scripting VulnerabilitiesKEV80Now
- CVE-2020-3187Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Web Services Path Traversal Vulnerability65This week
- CVE-2024-20481A vulnerability in the Remote Access VPN (RAVPN) service of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat DefeKEV58Plan
- CVE-2022-20759Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software Web Services Interface Privilege Escalation Vulnerability44Plan
- CVE-2020-3562Cisco Firepower 2100 Series SSL/TLS Inspection 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.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:snort | 2.9.20-0+deb10u1 · Debian:10 | Package registry (OSV) |
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-693 · Protection Mechanism FailureCVSS vector
CVSS:3.1/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.
Attack patterns (CAPEC)
- Accessing Functionality Not Properly Constrained by ACLsCAPEC-1likelihood: High · High
- Cross Site TracingCAPEC-107likelihood: Medium · Very High
- Directory IndexingCAPEC-127likelihood: High · Medium
- Using Malicious FilesCAPEC-17likelihood: High · Very High
- Encryption Brute ForcingCAPEC-20likelihood: Low · Low
- Exploiting Trust in ClientCAPEC-22likelihood: High · High
- Escaping a Sandbox by Calling Code in Another LanguageCAPEC-237likelihood: Low · Very High
- Using Unpublished Interfaces or FunctionalityCAPEC-36likelihood: Medium · High
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (2 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.