CVE-2026-21914 Junos OS: SRX Series: A specifically malformed GTP message will cause an FPC crash
An unauthenticated attacker can crash the SRX Series FPC by sending a malformed GTP message, causing a complete traffic outage.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-21914?
CVE-2026-21914 is a high-severity denial of service vulnerability in Juniper Junos, published on 15 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
An Improper Locking vulnerability in the GTP plugin of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (Dos).
If an SRX Series device receives a specifically malformed GPRS Tunnelling Protocol (GTP) Modify Bearer Request message, a lock is acquired and never released. This results in other threads not being able to acquire a lock themselves, causing a watchdog timeout leading to FPC crash and restart. This issue leads to a complete traffic outage until the device has automatically recovered.
This issue affects Junos OS on SRX Series:
* all versions before 22.4R3-S8, * 23.2 versions before 23.2R2-S5, * 23.4 versions before 23.4R2-S6, * 24.2 versions before 24.2R2-S3, * 24.4 versions before 24.4R2-S2, * 25.2 versions before 25.2R1-S1, 25.2R2.
Weakness: CWE-667
Which versions are affected by CVE-2026-21914?
It affects 1 product.
Products include Juniper Junos.
How do I fix CVE-2026-21914?
No fix has been published for CVE-2026-21914 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-21914 being exploited?
There is no known exploitation of CVE-2026-21914 in the wild and no public exploit code.
Other vulnerabilities in Juniper Junos
- CVE-2023-36845 Juniper Junos OS EX Series and SRX Series PHP External Variable Modification
- CVE-2020-1631 Juniper Junos OS Path Traversal
- CVE-2025-21590 Juniper Junos OS Improper Isolation or Compartmentalization
- CVE-2023-36851 Juniper Junos OS SRX Series Missing Authentication for Critical Function
- CVE-2023-36844 Juniper Junos OS EX Series PHP External Variable Modification
Sources
Also known as GHSA-w5fv-m4rq-pgg2.