---
cve: "CVE-2026-48691"
severity: "HIGH"
cvss: 7.3
epss: "31%"
vendor: "n/a"
kev: false
exploited: false
published: "2026-05-26 17:16:53"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-12T00:46:34+02:00"
---

# CVE-2026-48691

> 7.3 HIGH · 🧪 PoC

## Beschreibung

FastNetMon Community Edition through 1.2.9 contains an integer overflow in the BGP AS_PATH attribute encoder. In src/bgp_protocol.hpp, the IPv4UnicastAnnounce::get_attributes() function computes attribute_length as 'sizeof(bgp_as_path_segment_element_t) + this->as_path_asns.size() * sizeof(uint32_t)' and stores it in a uint8_t field (line 600-605). Since uint8_t can only hold values 0-255, an AS_PATH containing more than 63 ASNs (2 + 64*4 = 258 > 255) causes silent truncation. The truncated length is used for buffer sizing, while the actual data written is the full untruncated amount, resulting in a heap buffer overflow. Similarly, the path_segment_length field at line 621 is also uint8_t, truncating with more than 255 ASNs.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Gering | warn |
| I Integrität | Gering | warn |
| A Verfügbarkeit | Gering | warn |

## Patch verfügbar (OSV)

- 394fbe06d112f9609d3d1cb10d60cbf98347c96a (Commit)

## Referenzen

- <https://github.com/pavel-odintsov/fastnetmon>
- <https://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hpp>
- <https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48691-bgp-as-path-overflow>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-48691) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_