CVE-2026-49017: In OpenStack Swift before 2.36.2 and 2.37.2, s3api middleware enters an infinite loop when processing a trunca

Routine

MEDIUM 6.5UPGRADE

CVE-2026-49017 is a medium-severity flaw (CVSS 6.5) affecting swift. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 o

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 71%)
CISA exploited list	No
Weakness	CWE-835
Published	2026-05-27
Last modified	2026-09-24

Publisher (CNA): MITRE · Vendor: openstack

Last updated 2026-09-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-27 02:16 UTCPublished CVE record published
2026-09-24 17:25 UTCUpdated Record last modified

openstack swift UPGRADE

Affected: >= 2.35.1 and < 2.35.3 · >= 2.36.0 and < 2.36.2 · >= 2.37.0 and < 2.37.2

Fixed in: 2.35.3, 2.36.2, 2.37.2

Safe to downgrade to: a release before 2.35.1

1. Check installed version

apt-cache policy swift || rpm -q swift || swift --version

2. UPGRADE to 2.35.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade swift

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade swift

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.35.1 (Debian / Ubuntu)

apt-cache madison swift sudo apt install swift=<VERSION_BEFORE_2.35.1> sudo apt-mark hold swift

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list swift sudo dnf downgrade swift-<VERSION_BEFORE_2.35.1> sudo dnf versionlock add swift

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-49017?

swift: upgrade to 2.35.3, 2.36.2, 2.37.2. Exact commands for each OS are on this page.

Is CVE-2026-49017 being exploited?

CVE-2026-49017 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-49017 affect?

CVE-2026-49017 affects swift. Severity is medium (CVSS 6.5). 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-serv

How urgent is CVE-2026-49017?

Priority 30/100. No elevated risk signals yet.

Software pages

AWS vulnerabilities · OpenStack vulnerabilities · Swift vulnerabilities

Related CVEs

CVE-2026-50221 MEDIUM 5.4 UPGRADE In OpenStack Swift before 2.37.2, proxy-server does not strip internal update headers (X-Container-Host, X-Con

References

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