CVE-2026-48685: Software Security Vulnerability Vulnerability

MODERATE
Advisory Identifier: GHSA-4h2g-xxvj-v3w5
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CVSS 6.5
CWE-130
Published
Advisory Summary

CVE-2026-48685 is a MODERATE (CVSS 6.5) security vulnerability vulnerability (CWE-130: Improper Handling of Length Parameter Inconsistency) affecting Software libraries in the Maven ecosystem. The weakness occurs when the product parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data.. Remediation is available in the latest vendor maintenance releases.

CVE-2026-48685 at a Glance

CVE Identifier CVE-2026-48685
GHSA Identifier GHSA-4h2g-xxvj-v3w5
Severity MODERATE
CVSS v3.1 Base Score 6.5
CWE Classification CWE-130: Improper Handling of Length Parameter Inconsistency
Affected Product Software
Package Ecosystem Maven
Published Date
Last Updated

Security Impact

CVSS: 6.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-48685

To remediate this vulnerability, upgrade all affected Software dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

mvn dependency:tree

How to Check if You Are Affected

To determine whether your Java application is affected by CVE-2026-48685, inspect your build dependencies using the Maven Dependency Plugin:

mvn dependency:tree

Analyze the terminal output to locate any version of Software in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: The mvn dependency:tree command inspects the resolved dependency graph declared in your project's POM files; it does not perform automated security scanning or inspect runtime dynamic classpaths. Always verify runtime container classpaths and shaded JARs.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-130: Improper Handling of Length Parameter Inconsistency, where the product parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data. In Software, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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.

References

NVD — CVE-2026-48685 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-48685
Software Source Repository REPOSITORY
https://github.com/pavel-odintsov/fastnetmon
Software Source Repository REPOSITORY
https://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hpp
Software Security Information SECURITY
https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48685-bgp-extended-length

Frequently Asked Questions

What is CVE-2026-48685?
CVE-2026-48685 is a security vulnerability in Software classified as a security vulnerability vulnerability under CWE-130: Improper Handling of Length Parameter Inconsistency.
Which Software versions are affected?
Affected versions include releases prior to current release patches.
What version fixes CVE-2026-48685?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
What is the CVSS score of CVE-2026-48685?
CVE-2026-48685 has a CVSS v3.1 base score of 6.5 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-48685?
CVE-2026-48685 is classified under CWE-130: Improper Handling of Length Parameter Inconsistency (The product parses a formatted message or structure, but it does not handle or incorrectly handles a length field that is inconsistent with the actual length of the associated data.).
How can I check Maven dependencies for CVE-2026-48685?
Run the dependency tree command: 'mvn dependency:tree'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-4h2g-xxvj-v3w5",
  "modified" : "2026-05-26T21:31:54Z",
  "published" : "2026-05-26T18:31:43Z",
  "aliases" : [ "CVE-2026-48685" ],
  "details" : "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.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-48685"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pavel-odintsov/fastnetmon"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pavel-odintsov/fastnetmon/blob/master/src/bgp_protocol.hpp"
  }, {
    "type" : "WEB",
    "url" : "https://lorikeetsecurity.com/blog/fastnetmon-cve-2026-48685-bgp-extended-length"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-130" ],
    "severity" : "MODERATE",
    "github_reviewed" : false,
    "github_reviewed_at" : null,
    "nvd_published_at" : "2026-05-26T16:16:26Z"
  }
}