CVE-2020-26877: ApiFest OAuth 2.0 Server 0.3.1 does not validate the redirect URI in accordance with RFC 6749 and is susceptib

Routine

MEDIUM 6.1DOWNGRADE

CVE-2020-26877 is a medium-severity flaw (CVSS 6.1) affecting oauth 2.0 server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

ApiFest OAuth 2.0 Server 0.3.1 does not validate the redirect URI in accordance with RFC 6749 and is susceptible to an open redirector attack. Specifically, it directly sends an authorization code to the redirect URI submitted with the authorization request, without checking whether the redirect URI is registered by the client who initiated the request. This allows an attacker to craft a request with a manipulated redirect URI (redirect_uri param

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.9% (top 42%)
CISA exploited list	No
Weakness	CWE-601
Published	2022-06-29
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: apifest

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

Am I affected?

Timeline

2022-06-29 14:15 UTCPublished CVE record published
2026-06-17 03:08 UTCUpdated Record last modified

apifest oauth 2.0 server DOWNGRADE

Affected: 0.3.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.3.1

1. Check installed version

apt-cache policy oauth-2.0-server || rpm -q oauth-2.0-server || oauth-2.0-server --version

2. No fixed release: DOWNGRADE to a release before 0.3.1 (Debian / Ubuntu)

apt-cache madison oauth-2.0-server sudo apt install oauth-2.0-server=<VERSION_BEFORE_0.3.1> sudo apt-mark hold oauth-2.0-server

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list oauth-2.0-server sudo dnf downgrade oauth-2.0-server-<VERSION_BEFORE_0.3.1> sudo dnf versionlock add oauth-2.0-server

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-2020-26877?

oauth 2.0 server: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-26877 being exploited?

CVE-2020-26877 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-2020-26877 affect?

CVE-2020-26877 affects oauth 2.0 server. Severity is medium (CVSS 6.1). ApiFest OAuth 2.0 Server 0.3.1 does not validate the redirect URI in accordance with RFC 6749 and is susceptible to an open redirector attack. Specifically, it directly sends an authorization code to the redirect URI submitted with the auth

How urgent is CVE-2020-26877?

Priority 36/100. No elevated risk signals yet.

References

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