CVE-2021-1223
HIGHEPSS 79th pctlDescription
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 an HTTP range header. An attacker could exploit this vulnerability by sending crafted HTTP packets through an affected device. A successful exploit could allow the attacker to bypass configured file policy for HTTP packets and deliver a malicious payload.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Exploit Intelligence
Elevated risk: more likely to be exploited than 79% of all known CVEs.
References
Related Vulnerabilities
Other CWE-693 (Protection Mechanism Failure) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2013-2465 | Critical | 9.8 | 99% | KEV + Ransom | - |
| CVE-2024-21412 | High | 8.1 | 95% | KEV + Ransom | Fix |
| CVE-2013-0431 | Medium | 5.3 | 90% | KEV + Ransom | - |
| CVE-2019-1003030 | Critical | 9.9 | 76% | KEV | - |
| CVE-2025-40536 | High | 8.1 | 72% | KEV | Fix |
| CVE-2025-0411 | High | 7.0 | 67% | KEV | Fix |
Common questions
How do I fix CVE-2021-1223?
Published advisories record a fix for 3 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.
Is CVE-2021-1223 being actively exploited?
Not that we know of. CVE-2021-1223 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 2.0% is the estimated probability that it will be exploited in the next 30 days. That is higher than 79% of all scored CVEs.
How severe is CVE-2021-1223?
CVE-2021-1223 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2021-1223 affect?
Published advisories record a fix for firepower threat defense (NVD), ios xe (NVD), snort (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2024-11-26.