CVE-2026-48686
Published: 26 May 2026
Summary
CVE-2026-48686 is a critical-severity Classic Buffer Overflow (CWE-120) vulnerability in Pavel-Odintsov Fastnetmon. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 7.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Platform-independent managed code eliminates the need for unchecked native buffer copies that are the root cause of classic buffer overflows.
Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Stack buffer overflow in BGP packet decoder enables remote arbitrary code execution via crafted network input to a publicly exposed service.
NVD Description
FastNetMon Community Edition through 1.2.9 contains a stack-based buffer overflow in the BGP NLRI (Network Layer Reachability Information) decoder. The function decode_bgp_subnet_encoding_ipv4_raw() in src/bgp_protocol.cpp reads prefix_bit_length directly from the BGP packet (line 99) without validating it is <= 32 for…
more
IPv4 prefixes. This value is passed to how_much_bytes_we_need_for_storing_certain_subnet_mask() which computes ceil(prefix_bit_length / 8), returning up to 32 bytes for a prefix_bit_length of 255. The result is used as the length argument to memcpy() (line 106), which copies into a 4-byte uint32_t stack variable (prefix_ipv4). This causes a stack buffer overflow of up to 28 bytes, which can be exploited for arbitrary code execution. Additionally, the unvalidated prefix_bit_length is passed to convert_cidr_to_binary_netmask_local_function_copy() (line 111), where a shift of (32 - cidr) with cidr > 32 causes undefined behavior.
Deeper analysisAI
Automated synthesis unavailable for this CVE.
Details
- CWE(s)
Affected Products
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-31842
Regulatory context (EU CRA / NIS2 / DORA / UK NIS Regulations)
EU Cyber Resilience Act — coordinated disclosure
Critical and high-severity vulnerabilities in products with digital elements may trigger coordinated-disclosure obligations under the EU Cyber Resilience Act (CRA, Regulation 2024/2847). Manufacturers placing products on the EU market must notify ENISA and the relevant CSIRTs without undue delay once active exploitation is known.