# CVE-2026-83813: Twisted: DNS Response Spoofing in twisted.names Due to Missing Source Address Validation


- **Severity:** Low 3.1 (`CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 23 Oct 2026
- **Updated:** 29 Oct 2026
- **Also known as:** AZL-111419, DEBIAN-CVE-2026-83813, ECHO-487e-7daf-726c, GHSA-jj36-9pvh-vj5r, UBUNTU-CVE-2026-83813

## What is CVE-2026-83813?

CVE-2026-83813 is a low-severity vulnerability in twisted, published on 23 Oct 2026. 

### Official description

Twisted is an event-based framework for internet applications, supporting Python 3.6+. Prior to 26.10.0rc1, twisted.names.dns.DNSDatagramProtocol accepts a UDP DNS response for a pending query when its 16-bit transaction ID matches but does not verify that the response came from the queried host and port. An attacker able to deliver a packet to the resolver's listening port with the correct transaction ID can inject a forged answer. The standard twisted.names.client.Resolver uses a new random source port for each query, increasing off-path attack complexity, while applications that reuse a DNSDatagramProtocol instance expose only the transaction-ID search space after the first query. A successful forgery can redirect hostname resolution and enable mail interception, server-side request forgery, or man-in-the-middle positioning. This issue is fixed in version 26.10.0rc1.

Weakness: CWE-346 (Origin Validation Error)

## Which versions are affected by CVE-2026-83813?

2 open source packages ship an affected version, including Twisted and twisted.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `Twisted` | PyPI | All versions | 26.10.0rc1 |
| `twisted` | PyPI | All versions | 26.10.0rc1 |

## How do I fix CVE-2026-83813?

Upgrade Twisted to 26.10.0rc1 or later.

## Is CVE-2026-83813 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-83813 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-83813 and fix it if it is affected.

What it is: CVE-2026-83813 is a low-severity vulnerability in twisted, published on 23 Oct 2026. 
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-83813 exists.

Affected packages and fixed versions:
- Twisted (PyPI): affected all versions; fixed in 26.10.0rc1
- twisted (PyPI): affected all versions; fixed in 26.10.0rc1

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-2026-83813/ (Markdown: https://insights.sbomify.com/CVE-2026-83813/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-83813
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-83813
- OSV: https://osv.dev/vulnerability/CVE-2026-83813

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-83813/
Summaries are generated and may contain mistakes; the official description above is the record.