CVE-2021-21877

CRITICALNVD 9.19.1—

9.1

Specially-crafted HTTP requests can lead to arbitrary command execution in “GET” requests. An attacker can make authenticated HTTP requests to trigger this vulnerability.

CVSS v3: 9.1
EG Score: 9.1(medium)
EPSS: 88.7%
KEV: Not listed

Published

December 22, 2021

Last Modified

November 21, 2024

References (2)

talos-cna@ciscohttps://talosintelligence.com/vulnerability_reports/TALOS-2021-1315
af854a3a-2127-422b-91ae-364da2661108https://talosintelligence.com/vulnerability_reports/TALOS-2021-1315

Weakness Classification(1)

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

CWE-78OS Command Injection

Data Freshness Timeline

(refreshed 10× in last 7d / 20× in last 30d)

Every time one of our enrichment pipelines (NVD, MITRE cvelistV5, EPSS, CISA KEV, GHSA, OSV, vendor advisories) ran against this CVE. Most recent first.

2026-06-05 22:45 UTCepss_batch
2026-06-05 22:45 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-02 20:11 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 22:29 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-31 00:15 UTCepss_batch
2026-05-29 13:42 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-27 13:39 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 05:58 UTCEG score recompute
2026-05-26 05:58 UTCGHSA enrichment
2026-05-25 07:07 UTCOSV refresh
2026-05-24 16:49 UTCepss_batch

Frequently asked(5)

What is CVE-2021-21877?

CVE-2021-21877 is a critical vulnerability published on December 22, 2021. Specially-crafted HTTP requests can lead to arbitrary command execution in “GET” requests. An attacker can make authenticated HTTP requests to trigger this vulnerability.

When was CVE-2021-21877 disclosed?

CVE-2021-21877 was first published in the National Vulnerability Database on December 22, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.

Is CVE-2021-21877 actively exploited?

CVE-2021-21877 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 88.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-21877?

CVE-2021-21877 has a CVSS v3 base score of 9.1 (NVD).

How do I remediate CVE-2021-21877?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-21877, 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.

Dependency Blast Radius

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CVE-2021-21877

📅 Published

🔄 Last Modified

🔗 References (2)

Weakness Classification(1)

Data Freshness Timeline

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-21877?

🔗 Related CVEs(same CWE)

Same CWE

Published

Last Modified

References (2)

Frequently asked(5)

Related CVEs(same CWE)