CVE-2026-49837Public exploitNetwork attack vector

Peer validation manipulation via cross-capability parsing

Published Sep 10, 2026 · Updated Sep 10, 2026

Protocol parsing in OSRG GoBGP 4.5.0 and earlier allows remote attackers to manipulate peer validation via malformed BGP OPEN messages. The generic capability parser records CapLen, but several concrete decoders read the full remaining buffer and consume bytes belonging to the next capability. Access to the BGP listener is required; the parsed AS value influences capability negotiation and session acceptance or rejection, with no reported code execution, disclosure, or process interruption.

CVSS severity5.9
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Protocol parsing in OSRG GoBGP 4.5.0 and earlier allows remote attackers to manipulate peer validation via malformed BGP OPEN messages. The generic capability parser records CapLen, but several concrete decoders read the full remaining buffer and consume bytes belonging to the next capability. Access to the BGP listener is required; the parsed AS value influences capability negotiation and session acceptance or rejection, with no reported code execution, disclosure, or process interruption.

The record

CVE
CVE-2026-49837
Published
Sep 10, 2026
Updated
Sep 10, 2026
Vendor
GoBGP
Product
GoBGP
Classifications
CWE-125
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 10, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 10, 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=< 4.6.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

GoBGP · GoBGPversion=< 4.6.0

Published CVSS scores

5.9GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

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-125Out-of-bounds Read

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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