CVE-2023-23943

Blind SSRF via server URL input in the Nextcloud Mail app

MEDIUM
4.3
CVSS Score
Published: February 6, 2023 at 08:18 PM UTC
Updated: June 17, 2026 at 05:38 AM UTC
1 product affected across 1 vendorMail

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Severity
MEDIUM4.3
Exploit prediction
EPSS 0.9%
SSVC
PoC

Description

Nextcloud mail is an email app for the nextcloud home server platform. In affected versions the SMTP, IMAP and Sieve host fields allowed to scan for internal services and servers reachable from within the local network of the Nextcloud Server. It is recommended that the Nextcloud Maill app is upgraded to 1.15.0 or 2.2.2. The only known workaround for this issue is to completely disable the nextcloud mail app.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Mail· Nextcloudnextcloud-app
95%
v < 1.15.02.2.0 ≤ v < 2.2.2
Affected range stops below 1.15.0, so it looks safe — our inference, not a vendor statement
Affected range stops below 2.2.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (5)

x_refsource_MISCExploitThird Party Advisory
https://hackerone.com/reports/1736390
x_refsource_MISCExploitThird Party Advisory
https://hackerone.com/reports/1741525
x_refsource_MISCExploitThird Party Advisory
https://hackerone.com/reports/1746582

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
ADJACENT_NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-918

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