# CVE-2026-88833: BusyBox udhcpc integer underflow in DHCP packet processing

Source: https://junglewise.ai/threats/cve-2026-88833-a-flaw-was-found-in-busybox-s-udhcpc-dhcp-client-when-processing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-88833 · Severity: medium · CVSS 6.5 · Published 2026-10-13

BusyBox's udhcpc is a lightweight DHCP client used on embedded devices and minimal systems to obtain network configuration. A flaw in its packet processing allows an attacker on the same network to send a malicious DHCP packet that crashes the client, causing loss of network connectivity. This denial of service affects any system relying on udhcpc for network setup.

Technologies: [Busybox](https://junglewise.ai/threats/technologies/busybox). Vendors: [Busybox](https://junglewise.ai/threats/vendors/busybox).

## Quick answers

**Is CVE-2026-88833 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-88833 being exploited in the wild.

**How severe is CVE-2026-88833?** Medium severity, with a CVSS score of 6.5, published 13 October 2026.

**Which products and versions are affected?** Busybox udhcpc component.

**Is there a fix for CVE-2026-88833?** No fixed version is recorded yet. If feasible, use udhcpc in LISTEN_KERNEL mode instead of LISTEN_RAW, or use an alternative DHCP client such as dhclient or systemd-networkd. Restrict DHCP traffic on the local network segment (for example using DHCP snooping on switches). If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-88833 attacked?** It is attacked from the adjacent network, in a software library.

**Am I affected by CVE-2026-88833?** Check whether you run Busybox at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix


If feasible, use udhcpc in LISTEN_KERNEL mode instead of LISTEN_RAW, or use an alternative DHCP client such as dhclient or systemd-networkd. Restrict DHCP traffic on the local network segment (for example using DHCP snooping on switches).

## Technical details

An integer underflow vulnerability in udhcpc's d4_recv_raw_packet() function occurs when the client processes raw DHCP packets: it replaces a validated packet length with an attacker-controlled value from the IP header without re-validation, leading to integer underflow when subtracting header sizes and a subsequent oversized memory copy operation. An attacker on the same Layer 2 network segment (adjacent network) can trigger reliable denial of service by sending a specially crafted packet, causing the DHCP client to crash and lose network configuration.

## Affected products

- BusyBox BusyBox udhcpc component

## Timeline

- 2026-10-13: disclosed

## References

- [https://access.redhat.com/downloads/content/package-browser/](https://access.redhat.com/downloads/content/package-browser/)
- [https://access.redhat.com/security/cve/CVE-2026-88833](https://access.redhat.com/security/cve/CVE-2026-88833)

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