---
cve: "CVE-2026-48685"
severity: "MEDIUM"
cvss: 6.5
epss: "0.3%"
vendor: "n/a"
kev: false
exploited: false
published: "2026-05-26 00:00:00"
tags: [cve, security, medium]
source: tsecurity.de CVE-Dossier
exported: "2026-09-20T00:02:48+02:00"
---

# CVE-2026-48685

> 6.5 MEDIUM · 🧪 PoC

## Beschreibung

FastNetMon Community Edition through 1.2.9 has out-of-bounds memory access because it incorrectly parses BGP path attributes with the extended length flag set. In src/bgp_protocol.hpp, the parse_raw_bgp_attribute() function correctly identifies when extended_length_bit is set and sets length_of_length_field to 2, but then reads only a single byte for the attribute value length (attribute_value_length = value[2] at line 173). Per RFC 4271 Section 4.3, when the Extended Length bit is set, the Attribute Length field is two octets and the value should be read as a 16-bit big-endian integer from value[2] and value[3]. As a result, any attribute longer than 255 bytes has its length silently truncated to the low byte (e.g., 300 bytes = 0x012C is read as 0x2C = 44 bytes). The remaining 256 bytes are then misinterpreted as subsequent attributes, causing cascading parse failures and potential out-of-bounds memory access.

## CVSS-Vektor

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

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

## 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-2026-48685-bgp-extended-length>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-48685) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_