CVE-2021-20873: Yappli is an application development platform which provides the function to access a requested URL using Cust

This month

HIGH 8.1UPGRADE

CVE-2021-20873 is a high-severity flaw (CVSS 8.1) affecting yappli. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Yappli is an application development platform which provides the function to access a requested URL using Custom URL Scheme. When Android apps are developed with Yappli versions since v7.3.6 and prior to v9.30.0, they are vulnerable to improper authorization in Custom URL Scheme handler, and may be directed to unintended sites via a specially crafted URL.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.9% (top 41%)
CISA exploited list	No
Weakness	CWE-862
Published	2021-12-28
Last modified	2026-06-17

Publisher (CNA): JPCERT/CC · Vendor: yappli

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

Am I affected?

Timeline

2021-12-28 02:15 UTCPublished CVE record published
2026-06-17 03:34 UTCUpdated Record last modified

yappli yappli UPGRADE

Affected: >= 7.3.6 and < 9.30.0

Fixed in: 9.30.0

Safe to downgrade to: a release before 7.3.6

1. Check installed version

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

2. UPGRADE to 9.30.0 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade yappli

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 7.3.6 (Debian / Ubuntu)

apt-cache madison yappli sudo apt install yappli=<VERSION_BEFORE_7.3.6> sudo apt-mark hold yappli

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

dnf --showduplicates list yappli sudo dnf downgrade yappli-<VERSION_BEFORE_7.3.6> sudo dnf versionlock add yappli

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-2021-20873?

yappli: upgrade to 9.30.0. Exact commands for each OS are on this page.

Is CVE-2021-20873 being exploited?

CVE-2021-20873 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-2021-20873 affect?

CVE-2021-20873 affects yappli. Severity is high (CVSS 8.1). Yappli is an application development platform which provides the function to access a requested URL using Custom URL Scheme. When Android apps are developed with Yappli versions since v7.3.6 and prior to v9.30.0, they are vulnerable to impr

How urgent is CVE-2021-20873?

Priority 43/100. High severity

Software pages

Android vulnerabilities

References

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