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CVE-2021-40856

64
FAUCET Score

CVE-2021-40856 is an authentication bypass vulnerability affecting Auerswald COMfortel 1400 IP and 2600 IP devices running firmware versions prior to 2.8G. This flaw, rated 7.5 HIGH on the CVSS scale, allows unauthenticated attackers to bypass security measures by manipulating URLs with the "/about/../" substring, potentially leading to full compromise of confidentiality. While there is no evidence of active exploitation or KEV listing, public exploit templates exist for tools like Nuclei, and its high EPSS score indicates a significant likelihood of future exploitation. Despite its severity and ease of exploitation, there is currently minimal community discussion or media coverage surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2.8fCPE matchmatch criteria
cpe:2.3:o:auerswald:comfortel_3600_ip_firmware:*:*:*:*:*:*:*:*
<= 2.8fCPE matchmatch criteria
cpe:2.3:o:auerswald:comfortel_2600_ip_firmware:*:*:*:*:*:*:*:*
<= 2.8fCPE matchmatch criteria
cpe:2.3:o:auerswald:comfortel_1400_ip_firmware:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
51.06%
Probability of exploitation in next 30 days
EPSS Percentile
98.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
Nuclei: CVE-2021-40856 · Dec 8, 2021
This CVE's current EPSS score of 0.5106 is in the 98th percentile among its peer group of 51,553 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

packetstormsecurity.com / files/165162/Auerswald-COMfortel-1400-2600-3600-IP-2.8F-Authentication-Bypass.html
ExploitThird Party AdvisoryVDB Entry
redteam-pentesting.de / en/advisories/-advisories-publicised-vulnerability-analyses
ExploitThird Party Advisory
redteam-pentesting.de / en/advisories/rt-sa-2021-004/-auerswald-comfortel-1400-2600-3600-ip-authentication-bypass
ExploitThird Party Advisory