# CVE-2026-95508: Libslirp: libslirp: heap buffer overflow in dhcpv6/tftp response builders on small interface mtu

CVE-2026-95508 is fixed in libslirp on 1 platform by DEBIAN-CVE-2026-95508 (version 4.9.5-1), released September 29, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-95508
- Priority: High
- CVSS: 7.4 (Moderate)
- EPSS: 0.0057
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 22, 2026
- Weakness: Out-of-bounds Write
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-95508

## Description

A heap-based buffer overflow was found in the DHCPv6 and TFTP response builders of libslirp. When the host is configured with a small interface MTU, a guest-supplied DHCPv6 CLIENTID option or TFTP blksize option can overflow the reply buffer with attacker-controlled content and length, resulting in denial of service and potentially arbitrary code execution in the host process. The default interface MTU is not affected.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libslirp Debian 14 | 4.9.5-1 | [DEBIAN-CVE-2026-95508](https://patchblox.com/security/data/fix/linux/debian-cve-2026-95508.md) | Sep 29, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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