# CVE-2026-85078: sanic chunked trailer request smuggling allows hidden second request execution

> Remote attackers can execute hidden second requests via HTTP request smuggling in Sanic, potentially bypassing security controls or executing code.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** GHSA-wmj6-g64g-j7q5, PYSEC-2026-4162

## What is CVE-2026-85078?

CVE-2026-85078 is a medium-severity vulnerability in sanic-org sanic, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Sanic is an opensource python web server/framework. In version 25.12.0, Sanic's core HTTP/1.1 chunked-body handling does not fully consume the trailer-part after the terminating zero chunk before reusing the keep-alive connection buffer. A remote unauthenticated client can place attacker-controlled bytes in that trailer region, causing Sanic to parse and route them as a hidden second request after the outer request. This breaks HTTP request-boundary integrity and can provide a request-smuggling primitive when Sanic is deployed behind intermediaries. This issue is fixed in version 25.12.1.

Weakness: CWE-444 (Inconsistent Interpretation of HTTP Requests)

## Which versions are affected by CVE-2026-85078?

5 open source packages ship an affected version, including sanic.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `sanic` | PyPI | All versions | 24.12.1, 25.12.1 |
| `sanic` | PyPI | All versions | 24.12.1 |
| `sanic` | PyPI | All versions | 24.12.1 |
| `sanic` | PyPI | From 25.12.0 | 25.12.1 |
| `sanic` | PyPI | From 25.12.0 | 25.12.1 |

## How do I fix CVE-2026-85078?

Upgrade sanic to a fixed version for your release line: 24.12.1 or 25.12.1.

## Is CVE-2026-85078 being exploited?

There is no known exploitation of CVE-2026-85078 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-85078 and fix it if it is affected.

What it is: CVE-2026-85078 is a medium-severity vulnerability in sanic-org sanic, published on 17 Sep 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-2026-85078 in the wild and no public exploit code.

Affected packages and fixed versions:
- sanic (PyPI): affected all versions; fixed in 24.12.1, 25.12.1
- sanic (PyPI): affected all versions; fixed in 24.12.1
- sanic (PyPI): affected all versions; fixed in 24.12.1
- sanic (PyPI): affected from 25.12.0; fixed in 25.12.1
- sanic (PyPI): affected from 25.12.0; fixed in 25.12.1

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-2026-85078/ (Markdown: https://insights.sbomify.com/CVE-2026-85078/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-85078
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-85078
- OSV: https://osv.dev/vulnerability/CVE-2026-85078

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-85078/
Summaries are generated and may contain mistakes; the official description above is the record.