# CVE-2026-57030: Junos OS: SRX Series: Flow sessions are not getting cleared leading to a DoS

> An unauthenticated attacker can trigger a race condition in the packet forwarding engine, causing flow session accumulation and subsequent denial of service.

- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:U/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:** 9 Jul 2026
- **Updated:** 10 Jul 2026
- **Also known as:** GHSA-6hx5-3rjf-rm36

## What is CVE-2026-57030?

CVE-2026-57030 is a high-severity vulnerability in Juniper Junos, published on 9 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') vulnerability in the packet forwarding engine (PFE) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS).

As part of the stateful traffic processing on SRX Series devices flows are being established, and removed when not needed anymore. During the removal process the timeout of a flow should be set to 3 seconds and consequentially the flow should be removed shortly after. Due to a race condition occurring when setting the timeout there is a chance (the exact conditions are outside the attackers control) that the timeout is instead set to a very high value of larger than 10,000 seconds:

user@host> show security flow session | match timeout
Session ID: 98784248524, Policy name: PROD-FLOW/4, HA State: Active, Timeout: 85250, Session State: Valid

This will lead to an accumulation of flows which can be observed by an ever-increasing value of invalidated sessions in the output of 'show security flow session summary':

user@host> show security flow session summary | match invalid
Invalidated sessions: 216931These sessions can't be cleared manually with the 'clear security flow session' command, which will either lead to forwarding to stop (and the system needs to be manually recovered with a reboot) or to a flowd core and automatic reboot.

This issue affects Junos OS on SRX Series:

  *  24.2 versions before 24.2R2-S3,
  *  24.4 versions before 24.4R2-S1, 24.4R2-S2,
  *  25.2 versions before 25.2R1-S2, 25.2R2.

This issue does not affect releases earlier than 24.2R1;

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization)

## Which versions are affected by CVE-2026-57030?

It affects 1 product.


Products: Juniper Junos.

## How do I fix CVE-2026-57030?

No fix has been published for CVE-2026-57030 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-57030 being exploited?

There is no known exploitation of CVE-2026-57030 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-2026-57030 and fix it if it is affected.

What it is: CVE-2026-57030 is a high-severity vulnerability in Juniper Junos, published on 9 Jul 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-2026-57030 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-2026-57030/ (Markdown: https://insights.sbomify.com/CVE-2026-57030/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-57030
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-57030
- OSV: https://osv.dev/vulnerability/CVE-2026-57030

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-57030/
Summaries are generated and may contain mistakes; the official description above is the record.