Junos OS: Heap-based buffer overflow in VXLAN Gateway Daemon (vgd)
Summary
A heap-based buffer overflow in the VXLAN Gateway Daemon (vgd) of Junos OS can be triggered by a crafted OVSDB message. An attacker with control of a malicious or compromised SDN controller can cause a complete outage of the OVSDB control plane and possibly execute code remotely. The flaw only applies when the OVSDB controller configuration (protocols ovsdb controller) is in use.
Affected
- Junos OS versions before 23.2R2-S7.7
- Junos OS 23.4 before 23.4R2-S8.13
- Junos OS 24.2 before 24.2R2-S5.5
- Junos OS 24.4 before 24.4R2-S5
- Junos OS 25.2 before 25.2R2-S2
- Junos OS 25.4 before 25.4R1-S3
- Junos OS 26.2 before 26.2R1-S2
- Default configuration is not affected.
Fixed in
- Junos OS 23.2R2-S7.7, 23.4R2-S8.13, 24.2R2-S5.5, 24.4R2-S5, 25.2R2-S2, 25.4R1-S3, 25.4R2, 26.2R1-S2, 26.2R2, 26.4R1 and all subsequent releases.
- Releases 23.2, 23.4 and 24.2 have been respun; previously published versions were rebuilt.
Workaround
Unknown. The vendor states that there are no known workarounds.
Exploitation
- Juniper SIRT is not aware of any malicious exploitation.
- No public proof of concept was identified in the research notes.
- CISA SSVC: exploitation none, not automatable, total technical impact.
Our recommendation
- Check whether Junos OS devices use the OVSDB controller configuration (protocols ovsdb controller).
- If so, update to a fixed release listed above as soon as possible.
- Restrict which SDN controllers may connect and monitor OVSDB sessions for anomalies.
- Review the full Juniper security bulletin JSA112188, as it contains further vulnerabilities.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Juniper Security Bulletin JSA112188 supportportal.juniper.net
- VulnRichment CVE-2026-103994 vulners.com
- Strix CVE-2026-103994 www.strix.ai
- VulDB 420098 vuldb.com
- Juniper Junos OS multiple vulnerabilities (HKCERT) www.hkcert.org
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 1 Nov 2026, 03:01.
Original description (NVD)
A Heap-based Buffer Overflow vulnerability in the VXLAN Gateway Daemon (vgd) of Juniper Networks Junos OS allows a malicious or compromised SDN-controller to cause a complete outage of the OVSDB control plane and possibly remote code execution.
NVD references (1)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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