CVE-2020-7965: flaskparser.py in Webargs 5.x through 5.5.2 doesn't check that the Content-Type header is application/json whe

This month

HIGH 8.8UPGRADE

CVE-2020-7965 is a high-severity flaw (CVSS 8.8) affecting webargs. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

flaskparser.py in Webargs 5.x through 5.5.2 doesn't check that the Content-Type header is application/json when receiving JSON input. If the request body is valid JSON, it will accept it even if the content type is application/x-www-form-urlencoded. This allows for JSON POST requests to be made across domains, leading to CSRF.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.6% (top 51%)
CISA exploited list	No
Weakness	CWE-352
Published	2020-01-29
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: webargs project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-01-29 15:15 UTCPublished CVE record published
2026-06-17 03:25 UTCUpdated Record last modified

webargs project webargs UPGRADE

Affected: >= 5.0.0 and <= 5.5.2

Fixed in: newer than 5.5.2

Safe to downgrade to: a release before 5.0.0

1. Check installed version

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

2. UPGRADE to newer than 5.5.2 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade webargs

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 5.0.0 (Debian / Ubuntu)

apt-cache madison webargs sudo apt install webargs=<VERSION_BEFORE_5.0.0> sudo apt-mark hold webargs

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

dnf --showduplicates list webargs sudo dnf downgrade webargs-<VERSION_BEFORE_5.0.0> sudo dnf versionlock add webargs

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-2020-7965?

webargs: upgrade to newer than 5.5.2. Exact commands for each OS are on this page.

Is CVE-2020-7965 being exploited?

CVE-2020-7965 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-2020-7965 affect?

CVE-2020-7965 affects webargs. Severity is high (CVSS 8.8). flaskparser.py in Webargs 5.x through 5.5.2 doesn't check that the Content-Type header is application/json when receiving JSON input. If the request body is valid JSON, it will accept it even if the content type is application/x-www-form-ur

How urgent is CVE-2020-7965?

Priority 43/100. High severity

Related CVEs

CVE-2019-9710 HIGH 8.1 UPGRADE An issue was discovered in webargs before 5.1.3, as used with marshmallow and other products

References

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