# CVE-2026-49017: OpenStack Swift: s3api middleware enters an infinite loop when processing a truncated aws-chunked PUT request body

> An authenticated attacker can cause a denial of service in OpenStack Swift by sending truncated aws-chunked PUT requests, exhausting proxy-server workers.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 May 2026
- **Updated:** 2 Jun 2026
- **Also known as:** DEBIAN-CVE-2026-49017, GHSA-g7jq-j257-rww2, PYSEC-2026-3080, UBUNTU-CVE-2026-49017, USN-8821-1

## What is CVE-2026-49017?

CVE-2026-49017 is a high-severity denial of service vulnerability in OpenStack Swift, published on 27 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

In OpenStack Swift before 2.36.2 and 2.37.2, s3api middleware enters an infinite loop when processing a truncated aws-chunked PUT request body. The StreamingInput class repeatedly appends an empty buffer and re-reads, causing the proxy-server worker handling the request to become permanently unresponsive with increasing CPU and memory consumption. An authenticated attacker can systematically exhaust all proxy-server workers, resulting in denial of service. The defect was introduced in Swift 2.36.0.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2026-49017?

5 open source packages ship an affected version, including swift. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `swift` | PyPI | From 2.36.0 to 2.36.1 | None |
| `swift` | PyPI | From 2.36.0 to 2.36.1 | None |
| `swift` | PyPI | From 2.36.0 to 2.36.1 | None |
| `swift` | PyPI | From 2.37.0 to 2.37.1 | None |
| `swift` | PyPI | From 2.37.0 to 2.37.1 | None |

Products: Openstack Swift.

## How do I fix CVE-2026-49017?

Upgrade to a fixed version.

## Is CVE-2026-49017 being exploited?

There is no known exploitation of CVE-2026-49017 in the wild and no public exploit code.

## Other vulnerabilities in OpenStack Swift

- [CVE-2016-0737](https://insights.sbomify.com/CVE-2016-0737/): OpenStack Object Storage (Swift) allows remote attackers to cause a denial of service (high 7.5)
- [CVE-2016-0738](https://insights.sbomify.com/CVE-2016-0738/): OpenStack Object Storage (Swift) allows remote attackers to cause a denial of service (high 7.5)
- [CVE-2013-6396](https://insights.sbomify.com/CVE-2013-6396/): Python Swift client is vulnerable to Missing SSL Certificate Check (medium 5.8)
- [CVE-2026-50221](https://insights.sbomify.com/CVE-2026-50221/): OpenStack Swift vulnerable to authenticated server-side request forgery (medium 5.3)
- [CVE-2015-5223](https://insights.sbomify.com/CVE-2015-5223/): OpenStack Object Storage (Swift) Sensitive Data Exposure (medium 5.0)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-49017 and fix it if it is affected.

What it is: CVE-2026-49017 is a high-severity denial of service vulnerability in OpenStack Swift, published on 27 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-49017 in the wild and no public exploit code.

Affected packages and fixed versions:
- swift (PyPI): affected from 2.36.0 up to 2.36.1; no fix listed
- swift (PyPI): affected from 2.36.0 up to 2.36.1; no fix listed
- swift (PyPI): affected from 2.36.0 up to 2.36.1; no fix listed
- swift (PyPI): affected from 2.37.0 up to 2.37.1; no fix listed
- swift (PyPI): affected from 2.37.0 up to 2.37.1; no fix listed

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-2026-49017/ (Markdown: https://insights.sbomify.com/CVE-2026-49017/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49017
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49017
- OSV: https://osv.dev/vulnerability/CVE-2026-49017

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-49017/
Summaries are generated and may contain mistakes; the official description above is the record.