# CVE-2026-101955: Junos OS: SRX Series: Malformed DNS packet causes service disruption when UTM Anti-Spam SBL is used

> Unauthenticated remote attackers can execute arbitrary code or cause denial of service via malformed DNS packets when UTM Anti-Spam SBL is enabled on Juniper SRX devices.

- **Severity:** Critical 9.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Oct 2026
- **Updated:** 16 Oct 2026
- **Also known as:** GHSA-rqrg-xm4f-h8pg

## What is CVE-2026-101955?

CVE-2026-101955 is a critical memory corruption vulnerability in Juniper Networks Junos OS, published on 14 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

A Stack-based Buffer Overflow vulnerability in the UTM Anti-Spam SBL of Juniper Networks Junos OS on SRX series allows an unauthenticated remote attacker to cause arbitrary code execution or a denial of service via a injected malformed DNS packet when Anti-Spam SBL inspection is enabled.

Weakness: CWE-121 (Stack-based Buffer Overflow)

## Which versions are affected by CVE-2026-101955?


## How do I fix CVE-2026-101955?

No fix has been published for CVE-2026-101955 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-101955 being exploited?

There is no known exploitation of CVE-2026-101955 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-101955 and fix it if it is affected.

What it is: CVE-2026-101955 is a critical memory corruption vulnerability in Juniper Networks Junos OS, published on 14 Oct 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-2026-101955 in the wild and no public exploit code.

Affected product: Juniper Networks Junos OS. 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-2026-101955/ (Markdown: https://insights.sbomify.com/CVE-2026-101955/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-101955
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-101955
- OSV: https://osv.dev/vulnerability/CVE-2026-101955

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-101955/
Summaries are generated and may contain mistakes; the official description above is the record.