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Vulnerabilities

Vulnerability · CVE-2026-48689

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).

Published May 26, 2026 · catalog updated Jul 24, 2026 · FastNetMon Community Edition through

Check if you run it

No confirmed exploitation is on record for CVE-2026-48689. EPSS is 0.91%. Act only if a listed version of FastNetMon Community Edition through is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (FastNetMon Community Edition through).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Critical9.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.91%
Remediation
Advisory link
Affected products
cpe pavel-odintsov/fastnetmon

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe pavel-odintsov/fastnetmonversion unspecified

How to fix CVE-2026-48689

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-48689. EPSS is 0.91%. Act only if a listed version of FastNetMon Community Edition through is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-122: Heap-based Buffer Overflow; CWE-193; CWE-787: Out-of-bounds Write. EPSS 0.91%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 26, 2026 · NIST NVD

    Detected

    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

  2. Jul 24, 2026 · NIST NVD

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2026-48689

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-48689

    30-day exploitation probability 0.9%

    first.org
  • NIST NVDVulnerability recordCVE-2026-48689

    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_

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.