Multiple Cisco Products Snort HTTP Detection Engine File Policy Bypass Vulnerability
Priority LOW 36CWE-755Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · Low · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA.
Summary
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 handling of specific HTTP header parameters. 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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.01728 77th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Cisco | Cisco Firepower Threat Defense Software | all versions | — | No fix listed | CNA |
- Cisco Firepower Threat Defense Software VendorCisco Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 23
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:cisco:secure_firewall_threat_defense:*:*:*:*:*:*:*:* | before 6.4.0.12; 6.5.0 to before 6.6.4; 6.7.0 to before 6.7.0.2 | Vulnerable | Cisco |
| cpe:2.3:a:cisco:ios_xe:*:*:*:*:*:*:*:* | 16.12 to before 16.12.5 | Vulnerable | Cisco |
| cpe:2.3:a:snort:snort:*:*:*:*:*:*:*:* | before 2.9.17.1 | Vulnerable | Snort |
| cpe:2.3:o:cisco:ios_xe:*:*:*:*:*:*:*:* | 17.1 to before 17.3.3; 17.4 to before 17.4.1 | Vulnerable | Cisco |
| cpe:2.3:h:cisco:1100-4g\/6g_integrated_services_router:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:1101_integrated_services_router:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:1109_integrated_services_router:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:1111x_integrated_services_router:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:111x_integrated_services_router:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:1120_integrated_services_router:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
- cpe:2.3:a:cisco:secure_firewall_threat_defense:*:*:*:*:*:*:*:* Versions before 6.4.0.12; 6.5.0 to before 6.6.4; 6.7.0 to before 6.7.0.2 Vulnerable ·Cisco
- cpe:2.3:a:cisco:ios_xe:*:*:*:*:*:*:*:* Versions 16.12 to before 16.12.5 Vulnerable ·Cisco
- cpe:2.3:a:snort:snort:*:*:*:*:*:*:*:* Versions before 2.9.17.1 Vulnerable ·Snort
- cpe:2.3:o:cisco:ios_xe:*:*:*:*:*:*:*:* Versions 17.1 to before 17.3.3; 17.4 to before 17.4.1 Vulnerable ·Cisco
- cpe:2.3:h:cisco:1100-4g\/6g_integrated_services_router:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:1101_integrated_services_router:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:1109_integrated_services_router:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:1111x_integrated_services_router:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:111x_integrated_services_router:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:1120_integrated_services_router:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
Show 13 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:h:cisco:1160_integrated_services_router:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:3000_integrated_services_router:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:4221_integrated_services_router:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:4331_integrated_services_router:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:4431_integrated_services_router:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:4461_integrated_services_router:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:c8200-1n-4t:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:c8200l-1n-4t:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:catalyst_8300-1n1s-4t2x:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:catalyst_8300-1n1s-6t:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:catalyst_8300-2n2s-4t2x:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:catalyst_8300-2n2s-6t:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:catalyst_8500l:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
- cpe:2.3:h:cisco:1160_integrated_services_router:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:3000_integrated_services_router:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:4221_integrated_services_router:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:4331_integrated_services_router:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:4431_integrated_services_router:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:4461_integrated_services_router:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:c8200-1n-4t:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:c8200l-1n-4t:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:catalyst_8300-1n1s-4t2x:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:catalyst_8300-1n1s-6t:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:catalyst_8300-2n2s-4t2x:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:catalyst_8300-2n2s-6t:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:catalyst_8500l:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2021-1495
- 2026-10-03 Alias added: GHSA-qp86-f9fh-jg8p
References
More Cisco Ios Xe vulnerabilities
- TI-2023-06904 Cisco is providing an update for the ongoing investigation into observed exploitation of… KEVCVSS 3.1CRITICAL 10.0
- TI-2018-00122 Memory corruption in Cisco IOS and IOS XE KEVCVSS 3.1CRITICAL 9.8
- TI-2017-02977 Improper input validation in Cisco IOS and IOS XE Software KEVCVSS 3.1CRITICAL 9.8
- TI-2018-00135 Memory corruption in Cisco IOS, IOS XE, and IOS XR KEVCVSS 3.1HIGH 8.8
- TI-2017-04498 Memory corruption in Cisco IOS KEVCVSS 3.1HIGH 8.8
- TI-2017-04497 Memory corruption in Cisco IOS XE Software KEVCVSS 3.1HIGH 8.8
Sources
- CVE-2021-1495 · CVE Program
- CVE-2021-1495 · NVD
- FIRST EPSS
- GHSA-qp86-f9fh-jg8p · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences