CVE-2018-1000831

K9Mail version <= v5.600 contains a XML External Entity (XXE) vulnerability in WebDAV response parser that can result in Disclosure of confidential data, denial of service, SSRF, port scanning. This attack appear to be exploitable via malicious WebDAV server or intercept the reponse of a valid WebDAV server.

Published: 2018-12-20 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2018-1000831 is rated High Risk (68.6/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 1.91%). EPSS rose +1.66% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2018-1000831

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.24% 1.91% +1.66%
2 2025-03-30 0.48% 0.24% -0.23%
3 2025-03-29 — 0.48% —

Full EPSS history (6 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2018-1000831

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
10.0 3.0 CRITICAL
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 6.0 [email protected]
7.5 2.0 HIGH
AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 6.4 [email protected]

Weakness enumeration for CVE-2018-1000831

Affected software / configurations for CVE-2018-1000831

Vendor Product Version Raw CPE
k9mail k-9_mail <= 5.600 cpe:2.3:a:k9mail:k-9_mail:*:*:*:*:*:*:*:*

References for CVE-2018-1000831

URL Tags
https://0dd.zone/2018/10/28/k9mail-XXE-MitM/ Third Party Advisory
https://github.com/k9mail/k-9/issues/3681 Issue Tracking Third Party Advisory
cvelogic Threat Intelligence