CVE-2026-41642Public exploitNetwork attack vector

Daemon crash via shadowed BGP validation error

Published May 7, 2026 · Updated May 7, 2026

Nil pointer dereference in GoBGP 4.3.0 allows remote attackers with an established BGP peering session to crash the daemon. In pkg/server/fsm.go, recvMessageloop keeps the outer nil error after ValidateUpdateMsg rejects an unknown well-known path attribute, then calls Error on it. A configured peer that completes the BGP handshake can terminate the entire routing process with one malformed UPDATE, not merely reset its session.

CVSS severity7.5
High
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Nil pointer dereference in GoBGP 4.3.0 allows remote attackers with an established BGP peering session to crash the daemon. In pkg/server/fsm.go, recvMessageloop keeps the outer nil error after ValidateUpdateMsg rejects an unknown well-known path attribute, then calls Error on it. A configured peer that completes the BGP handshake can terminate the entire routing process with one malformed UPDATE, not merely reset its session.

The record

CVE
CVE-2026-41642
Published
May 7, 2026
Updated
May 7, 2026
Vendor
GoBGP
Product
GoBGP
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 7, 2026CVE publishedPublication date reported by the CVE source.
  2. May 7, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion== 4.3.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

GoBGP · GoBGPversion== 4.3.0

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

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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