CVE-2021-1224

MEDIUMNVD 5.85.8—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.8 under NVD CVSS v3. EPSS exploit probability: 2.0%, top 21% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
5.8
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 2%CVSS: 5.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Multiple Cisco products are affected by a vulnerability with TCP Fast Open (TFO) when used in conjunction with 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 the HTTP payload if it is contained at least partially within the TFO connection handshake. An attacker could exploit this vulnerability by sending crafted TFO packets with an HTTP payload through an affected device. A successful exploit could allow the attacker to bypass configured file policy for HTTP packets and deliver a malicious payload.

CVSS v3
5.8
EG Score
5.8(medium)
EG Risk
—
EPSS
78.7%
KEV
Not listed

Published

January 13, 2021

Last Modified

November 26, 2024

References (6)

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 46× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 22:42 UTCEG score recompute▲ 0.50
  2. 2026-07-22 14:05 UTCEPSS rescore
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  65. 2026-05-27 13:39 UTCEPSS rescore
  66. 2026-05-26 22:06 UTCEG score recompute
  67. 2026-05-26 22:06 UTCGHSA enrichment
  68. 2026-05-26 13:42 UTCEPSS rescore
  69. 2026-05-26 13:42 UTCEPSS rescore
  70. 2026-05-26 07:17 UTCEPSS rescore
  71. 2026-05-26 07:17 UTCEPSS rescore
  72. 2026-05-24 21:12 UTCOSV refresh
  73. 2026-05-24 16:49 UTCEPSS rescore

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2021-1224?
CVE-2021-1224 is a medium vulnerability published on January 13, 2021. Multiple Cisco products are affected by a vulnerability with TCP Fast Open (TFO) when used in conjunction with 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 the HTTP…
When was CVE-2021-1224 disclosed?
CVE-2021-1224 was first published in the National Vulnerability Database on January 13, 2021, with the most recent update on November 26, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-1224 actively exploited?
CVE-2021-1224 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 78.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-1224?
CVE-2021-1224 has a CVSS v3 base score of 5.8 (NVD).
How do I remediate CVE-2021-1224?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-1224, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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