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GHSA-wwv8-cqpr-vx3m

HighCVSS 7.2 / 10
Published Mar 25, 2026·Last modified Mar 27, 2026
Affected Components(0)

No affected components available

Description

Summary

exec_cmd() in modoboa/lib/sysutils.py always runs subprocess calls with shell=True. Since domain names flow directly into shell command strings without any sanitization, a Reseller or SuperAdmin can include shell metacharacters in a domain name to run arbitrary OS commands on the server.

Details

The root cause is in modoboa/lib/sysutils.py:31:

kwargs["shell"] = True
process = subprocess.Popen(cmd, **kwargs)

When a create a domain is created with DKIM enabled, the domain name gets embedded into a shell command like this:

exec_cmd(f"openssl genrsa -out {dkim_storage_dir}/{domain.name}.pem {key_size}")

If the domain name contains something like $(id>/tmp/proof).example.com, the shell executes the injected command before running openssl.

The same pattern appears in several other places:

  • modoboa/admin/jobs.py:38 — mailbox rename via mv using full_address
  • modoboa/amavis/lib.py:202 — sa-learn using domain.name
  • modoboa/admin/models/mailbox.py:150 — doveadm user using full_address
  • modoboa/maillog/graphics.py:105–107 — rrdtool using domain.name
  • modoboa/webmail/models.py:54–57 — doveadm move/delete using account.email

PoC

  1. Deploy modoboa <= 2.7.0
  2. Log in as a Reseller or SuperAdmin
  3. Create a new domain named $(id>/tmp/proof).example.com with DKIM enabled
  4. SSH into the server and read /tmp/proof

Something like this will be displayed:

uid=0(root) gid=0(root) groups=0(root)

Confirmed on commit b521bcb4f (latest main at time of discovery).

Impact

An attacker with Reseller-level access (or higher) can execute arbitrary OS commands on the mail server — in a typical Modoboa deployment this means running as root. All six identified sinks are reachable through normal application workflows.

Risk Scores
Base Score
7.2

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs high-level or administrative privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.

Threat Intelligence
6.6

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.57%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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