# 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.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Jan 2026
- **Updated:** 15 Jan 2026
- **Also known as:** GHSA-w5fv-m4rq-pgg2

## 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 (Improper Locking)

## Which versions are affected by CVE-2026-21914?

It affects 1 product.


Products: 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.

## 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](https://insights.sbomify.com/CVE-2023-36845/): Juniper Junos OS EX Series and SRX Series PHP External Variable Modification (critical 9.8, exploited in the wild)
- [CVE-2020-1631](https://insights.sbomify.com/CVE-2020-1631/): Juniper Junos OS Path Traversal (high 8.8, exploited in the wild)
- [CVE-2025-21590](https://insights.sbomify.com/CVE-2025-21590/): Juniper Junos OS Improper Isolation or Compartmentalization (medium 6.7, exploited in the wild)
- [CVE-2023-36851](https://insights.sbomify.com/CVE-2023-36851/): Juniper Junos OS SRX Series Missing Authentication for Critical Function (medium 5.3, exploited in the wild)
- [CVE-2023-36844](https://insights.sbomify.com/CVE-2023-36844/): Juniper Junos OS EX Series PHP External Variable Modification (medium 5.3, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-21914 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-21914 in the wild and no public exploit code.

Affected product: Juniper Junos. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-21914/ (Markdown: https://insights.sbomify.com/CVE-2026-21914/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-21914
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-21914
- OSV: https://osv.dev/vulnerability/CVE-2026-21914

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-21914/
Summaries are generated and may contain mistakes; the official description above is the record.