Juniper Junos OS: Heap-based buffer overflow in eventd
Summary
A heap-based buffer overflow in eventd, the event daemon of Juniper Junos OS and Junos OS Evolved, affects several release trains. An unprivileged local user can send crafted IPC event messages to cause a denial of service or escalate privileges to root. Exploitation requires local access to the device, and no workaround exists. Juniper is not aware of malicious exploitation.
Affected
- Junos OS: releases 0 to < 23.2R2-S7.7, 23.4 to < 23.4R2-S8.13, 24.2 to < 24.2R2-S5.5, 24.4 to < 24.4R2-S5, 25.2 to < 25.2R2-S2, 25.4 to < 25.4R1-S3, 26.2 to < 26.2R1-S2 (per CNA record)
- Junos OS Evolved: releases 0 to < 23.2R2-S7.7-EVO, 23.4 to < 23.4R2-S8.11-EVO, 24.2 to < 24.2R2-S5.6-EVO, 24.4 to < 24.4R2-S5-EVO, 25.2 to < 25.2R2-S2-EVO, 25.4 to < 25.4R1-S3-EVO, 26.2 to < 26.2R1-S2-EVO, plus the 23.4X100, 25.2X100 and 25.4X300 train ranges listed in the CNA record
- Verify exact ranges in the Juniper advisory JSA112187.
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, 26.2R1-S2 and all subsequent releases
- Junos OS Evolved: 23.2R2-S7.7-EVO, 23.4R2-S8.11-EVO, 24.2R2-S5.6-EVO, 24.4R2-S5-EVO, 25.2R2-S2-EVO, 25.2X100-D35-EVO, 25.4R1-S3-EVO, 25.4X300-D40-EVO, 26.2R1-S2-EVO and all subsequent releases
- Fixed build for the 23.4X100 train: Unknown.
Workaround
No known workarounds.
Exploitation
- Juniper SIRT is not aware of malicious exploitation.
- Not listed in CISA KEV.
- CISA SSVC: exploitation none, not automatable, total technical impact.
- No public proof-of-concept found as of 1 Nov 2026.
Our recommendation
- Identify all Junos OS and Junos OS Evolved devices and their exact versions.
- Compare the versions with JSA112187 and upgrade to the fixed release for each train. For 23.4X100, check the advisory for the fixed build.
- Restrict local shell and login access, and limit the number of admin accounts.
- Check whether J-Web is enabled and restrict it to trusted hosts.
- Monitor for eventd crashes or restarts.
- Recheck KEV, NVD and vendor status in two weeks, as NVD analysis is pending.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- Juniper Security Advisory JSA112187 supportportal.juniper.net
- OpenCVE: CVE-2026-101927 app.opencve.io
- Strix: CVE-2026-101927 www.strix.ai
- Red Packet Security: CVE alert CVE-2026-101927 www.redpacketsecurity.com
- VulDB: CVE-2026-101927 vuldb.com
- SecurityOnline: Juniper patches critical Junos OS vulnerabilities securityonline.info
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, 08:10.
Original description (NVD)
A Heap-based Buffer Overflow vulnerability in eventd of Juniper Networks Junos OS and Junos OS Evolved on all platforms allows an unprivileged local attacker to cause a denial of service (DoS) or achieve privilege escalation to root via crafted IPC event messages.
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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