TI-2026-35974 Aliases CVE-2026-48689 GHSA-5444-f65m-f3c8

FastNetMon Community Edition through 1.2.9 contains an off-by-one heap-based buffer…

MEDIUM 50CWE-122Published 2026-05-26 · Updated 2026-05-27

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Code execution
Confidentiality · integrity · availability: High · High · High
Fix status: No fix listed

Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA. Impact type from CWE-122 and the CVSS impact.

Summary

FastNetMon Community Edition through 1.2.9 contains an off-by-one heap-based buffer overflow in the dynamic_binary_buffer_t class (src/dynamic_binary_buffer.hpp). Five methods (append_dynamic_buffer, append_data_as_pointer, append_data_as_object_ptr, memcpy_from_ptr, memcpy_from_object_ptr) use an incorrect bounds check of the form 'if (offset + length > maximum_internal_storage_size + 1)' instead of the correct 'if (offset + length > maximum_internal_storage_size)'. This allows writing exactly one byte past the end of the heap-allocated buffer. The class is used pervasively in BGP message encoding/decoding, NetFlow template processing, and Flow Spec NLRI construction. An attacker who can send network traffic (NetFlow, sFlow, IPFIX, or BGP) to a FastNetMon instance can trigger this overflow, potentially achieving arbitrary code execution by corrupting heap metadata. Notably, the append_byte() method uses the correct bounds check, confirming the inconsistency.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00677 52nd percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: Yes
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
—	—	all versions	—	No fix listed	CNA

— Vendor— Affected all versions Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:pavel-odintsov:fastnetmon:::::community:::*	up to 1.2.9	Vulnerable	pavel-odintsov

cpe:2.3:a:pavel-odintsov:fastnetmon:*:*:*:*:community:*:*:* Versions up to 1.2.9 Vulnerable ·pavel-odintsov

Remediation

No fixed version listed by the sources yet.

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product

Red Hat

Timeline

2026-10-02 Threatist record created from CVE-2026-48689
2026-10-03 Alias added: GHSA-5444-f65m-f3c8

References

Exploit 1

https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48689-dynamic-buffer-off-by-one

Other 2

TI-2026-35971 FastNetMon Community Edition through 1.2.9 contains a stack-based buffer overflow in the… CVSS 3.1CRITICAL 9.8
TI-2026-35976 FastNetMon Community Edition through 1.2.9 contains an integer overflow in the BGP… CVSS 3.1CRITICAL 9.8
TI-2026-35972 FastNetMon Community Edition through 1.2.9 contains an OS command injection vulnerability… CVSS 3.1CRITICAL 9.8
TI-2024-37109 An issue was discovered in FastNetMon Community Edition through 1.2.7. CVSS 3.1HIGH 7.5
TI-2024-37108 An issue was discovered in FastNetMon Community Edition through 1.2.7. CVSS 3.1HIGH 7.5
TI-2026-35980 FastNetMon Community Edition through 1.2.9 contains an OS command injection vulnerability… CVSS 3.1HIGH 8.1

See all 15 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences