CVE-2021-40856

HIGHNVD 7.59.0▲Elevated

7.5

Auerswald COMfortel 1400 IP and 2600 IP before 2.8G devices allow Authentication Bypass via the /about/../ substring.

CVSS v3: 7.5
EG Score: 9.0(high)
EPSS: 99.5%
KEV: Not listed

Published

December 13, 2021

Last Modified

November 21, 2024

References (6)

cve@mitrehttp://packetstormsecurity.com/files/165162/Auerswald-COMfortel-1400-2600-3600-IP-2.8F-Authentication-Bypass.html
cve@mitrehttps://www.redteam-pentesting.de/en/advisories/-advisories-publicised-vulnerability-analyses
cve@mitrehttps://www.redteam-pentesting.de/en/advisories/rt-sa-2021-004/-auerswald-comfortel-1400-2600-3600-ip-authentication-bypass
af854a3a-2127-422b-91ae-364da2661108http://packetstormsecurity.com/files/165162/Auerswald-COMfortel-1400-2600-3600-IP-2.8F-Authentication-Bypass.html
af854a3a-2127-422b-91ae-364da2661108https://www.redteam-pentesting.de/en/advisories/-advisories-publicised-vulnerability-analyses
af854a3a-2127-422b-91ae-364da2661108https://www.redteam-pentesting.de/en/advisories/rt-sa-2021-004/-auerswald-comfortel-1400-2600-3600-ip-authentication-bypass

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 5× in last 7d / 12× 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.

2026-06-01 13:50 UTCepss_batch
2026-06-01 13:50 UTCepss_batch
2026-05-29 13:42 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-28 13:43 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 13:42 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 07:17 UTCepss_batch
2026-05-26 06:34 UTCEG score recompute
2026-05-26 06:34 UTCGHSA enrichment

Publicly available exploits

(1 reference)

Working exploit code is in the public domain. Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

Nucleihttp/cves/2021/CVE-2021-40856.yaml
First seen Jan 1, 2021
Auerswald COMfortel 1400/2600/3600 IP - Authentication Bypass
Open source ↗

Frequently asked(5)

What is CVE-2021-40856?

CVE-2021-40856 is a high vulnerability published on December 13, 2021. Auerswald COMfortel 1400 IP and 2600 IP before 2.8G devices allow Authentication Bypass via the /about/../ substring.

When was CVE-2021-40856 disclosed?

CVE-2021-40856 was first published in the National Vulnerability Database on December 13, 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-2021-40856 actively exploited?

CVE-2021-40856 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 99.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.

What is the CVSS score of CVE-2021-40856?

CVE-2021-40856 has a CVSS v3 base score of 7.5 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 9.0.

How do I remediate CVE-2021-40856?

Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-40856, 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-2021-40856

📅 Published

🔄 Last Modified

🔗 References (6)

Weakness Classification(2)

Data Freshness Timeline

Publicly available exploits

❓ Frequently asked(5)

Dependency Blast Radius

Is Your Infrastructure Affected by CVE-2021-40856?

🔗 Related CVEs(same CWE)

Same CWE

Published

Last Modified

References (6)

Frequently asked(5)

Related CVEs(same CWE)