# CVE-2026-88830: BusyBox TLS heap buffer overflow in Montgomery reduction

Source: https://junglewise.ai/threats/cve-2026-88830-a-unit-confusion-in-busybox-tls-montgomery-reduction-buffer  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-23. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-88830 · Severity: high · CVSS 7.5 · Published 2026-09-23

BusyBox includes a lightweight TLS server utility that contains a buffer allocation bug in cryptographic processing. An unauthenticated attacker can crash the TLS server by sending a crafted TLS handshake message, causing denial of service. The vulnerability is limited to BusyBox's test ssl_server applet and does not affect standard BusyBox installations shipped in distributions.

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

## Quick answers

**Is CVE-2026-88830 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-88830 being exploited in the wild.

**How severe is CVE-2026-88830?** High severity, with a CVSS score of 7.5, published 23 September 2026.

**Which products and versions are affected?** Busybox affected versions not specified.

**Is there a fix for CVE-2026-88830?** No fixed version is recorded yet. Check the vendor's advisory in the references below. 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-2026-88830 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-88830?** 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.

## Technical details

A unit confusion in TLS Montgomery reduction buffer allocation (CWE-131) causes a pre-authentication heap buffer overflow when processing a ClientKeyExchange message. The attack is unauthenticated and network-accessible with no user interaction required, resulting in crash or potential code execution. Red Hat states that system mitigations (ASLR, PIE, RELRO, SELinux) prevent practical exploitation.

## Affected products

- BusyBox BusyBox affected versions not specified

## Timeline

- 2026-09-23: 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-2026-88830](https://access.redhat.com/security/cve/CVE-2026-88830)

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