CVE-2023-38406Network attack vector

Unauthenticated service crash via zero-length FlowSpec NLRI

Published Nov 6, 2023 · Updated Nov 4, 2025

Improper exceptional-condition handling in FRRouting before 8.4.3 allows remote attackers to crash bgpd with a zero-length BGP FlowSpec NLRI. The bgp_nlri_parse_flowspec parser passed a zero psize to bgp_fs_nlri_validate instead of rejecting the invalid length. Exploitation requires delivery of a crafted BGP FlowSpec message; the supported consequence is a routing-daemon crash and service interruption.

CVSS severity9.8
Critical
EPSS probability0.94%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper exceptional-condition handling in FRRouting before 8.4.3 allows remote attackers to crash bgpd with a zero-length BGP FlowSpec NLRI. The bgp_nlri_parse_flowspec parser passed a zero psize to bgp_fs_nlri_validate instead of rejecting the invalid length. Exploitation requires delivery of a crafted BGP FlowSpec message; the supported consequence is a routing-daemon crash and service interruption.

The record

CVE
CVE-2023-38406
Published
Nov 6, 2023
Updated
Nov 4, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-755, T1499.004
Attack vector
network
Privileges
Unavailable

Timeline

How it unfolded

  1. Nov 6, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 4, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-755Improper Handling of Exceptional Conditions
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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