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CVE-2021-20618

30
FAUCET Score

CVE-2021-20618 is a critical privilege chaining vulnerability affecting acmailer versions 4.0.2 and earlier, and acmailer DB versions 1.1.4 and earlier. This flaw allows remote, unauthenticated attackers to bypass security measures and gain administrative privileges, potentially leading to the compromise of sensitive server information. With a CVSS score of 9.8, it represents a severe risk due to its network-based attack vector, low complexity, and high impact on confidentiality, integrity, and availability. Despite its critical severity, there is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
<= 4.0.2CPE matchmatch criteria
cpe:2.3:a:acmailer:acmailer:*:*:*:*:*:*:*:*
<= 1.1.4CPE matchmatch criteria
cpe:2.3:a:acmailer:acmailer_db:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.30%
Probability of exploitation in next 30 days
EPSS Percentile
87.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0330 is in the 79th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

jvn.jp / en/jp/JVN35906450/index.html
Third Party Advisory
acmailer.jp / info/de.cgi
Vendor Advisory