CVE-2021-20873

Name: CVE-2021-20873
Creator: NVD / NIST
Published: 2021-12-28T02:15:06.907+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.1/10EPSS 0.84%

Last modified Jun 17, 2026

CVE-2021-20873 is a high-severity vulnerability rated 8.1/10 on the CVSS scale. 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.. EPSS estimates a 0.84% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

8.1/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

EPSS Probability

0.84%

53.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-862

Affected Software

Vendor	Product	Versions
Yappli	Yappli	>= 7.3.6, < 9.30.0

References

https://jvn.jp/en/jp/JVN66422035/index.htmlThird Party Advisory
https://support.yappli.co.jp/hc/ja/articles/4410249902745Vendor Advisory
https://jvn.jp/en/jp/JVN66422035/index.htmlThird Party Advisory
https://support.yappli.co.jp/hc/ja/articles/4410249902745Vendor Advisory

Timeline

Published: Dec 28, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-20873?

How severe is CVE-2021-20873?

CVE-2021-20873 has a CVSS score of 8.1/10 (HIGH severity). The EPSS model estimates a 0.84% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20873?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-20873?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST