# CVE-2026-102027: Juniper Junos OS buffer size calculation vulnerability in rpd

Source: https://junglewise.ai/threats/cve-2026-102027-an-incorrect-calculation-of-buffer-size-vulnerability-in-the  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-14. Updated: 2026-10-16  
License: CC BY 4.0 with a link back

CVE-2026-102027 · Severity: high · CVSS 7.5 · Published 2026-10-14

Juniper Junos OS is a networking operating system that manages routing and network traffic for enterprise networks. An incorrect buffer size calculation in the routing protocol daemon can be exploited by a configured external BGP neighbor to crash the routing service, causing network outages and potential loss of network connectivity.

Technologies: [Juniper Networks Junos OS](https://junglewise.ai/threats/technologies/juniper-networks-junos-os), [Juniper Networks Junos OS Evolved](https://junglewise.ai/threats/technologies/junos-os-evolved). Vendors: [Juniper Networks](https://junglewise.ai/threats/vendors/juniper-networks).

## Quick answers

**Is CVE-2026-102027 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-102027 being exploited in the wild.

**How severe is CVE-2026-102027?** High severity, with a CVSS score of 7.5, published 14 October 2026.

**Which products and versions are affected?** Juniper Networks Junos OS; Juniper Networks Junos OS Evolved.

**Is there a fix for CVE-2026-102027?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-102027 attacked?** It is attacked over the network, in an operating system.

**Am I affected by CVE-2026-102027?** Check whether you run Juniper Networks Junos OS or Juniper Networks Junos OS Evolved. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An incorrect buffer size calculation in the routing protocol daemon (rpd) allows a remote eBGP neighbor to trigger a denial of service by sending specially crafted BGP labeled-unicast UPDATE messages. The vulnerability is triggered only when multipath features are enabled in the affected system, requiring a pre-established BGP session with the device.

## Affected products

- Juniper Networks Junos OS
- Juniper Networks Junos OS Evolved

## Timeline

- 2026-10-14: disclosed

## References

- [https://supportportal.juniper.net/JSA112187](https://supportportal.juniper.net/JSA112187)

## Related threats

- [Juniper Networks Junos OS stack buffer overflow in BGP/EVPN](https://junglewise.ai/threats/cve-2026-101982-a-stack-based-buffer-overflow-vulnerability-in-the-routing)
- [Juniper Networks Junos OS stack buffer overflow in rpd](https://junglewise.ai/threats/cve-2026-101981-a-stack-based-buffer-overflow-vulnerability-in-the-routing)
- [Juniper Junos OS routing protocol daemon crash in ISO-VPN](https://junglewise.ai/threats/cve-2026-101952-an-improper-validation-of-consistency-within-input-vulnerability)
- [Juniper Networks Junos OS stack buffer overflow in BGP routing daemon](https://junglewise.ai/threats/cve-2026-102178-a-stack-based-buffer-overflow-vulnerability-in-the-bgp-routing)
- [Juniper Junos buffer overflow in SDK service process](https://junglewise.ai/threats/cve-2026-102176-a-buffer-copy-without-checking-size-of-input-classic-buffer)