CVE-2021-20747: Improper authorization in handler for custom URL scheme vulnerability in Retty App for Android versions prior

Q: How do I fix CVE-2021-20747?

retty: upgrade to 4.8.13; retty: upgrade to 4.11.14. Exact commands for each OS are on this page.

Q: Is CVE-2021-20747 being exploited?

CVE-2021-20747 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-20747 affect?

CVE-2021-20747 affects retty, retty. Severity is medium (CVSS 4.3). Improper authorization in handler for custom URL scheme vulnerability in Retty App for Android versions prior to 4.8.13 and Retty App for iOS versions prior to 4.11.14 allows a remote attacker to lead a user to access an arbitrary website v

Q: How urgent is CVE-2021-20747?

Priority 31/100. No elevated risk signals yet.

Routine

MEDIUM 4.3UPGRADEUPGRADE

CVE-2021-20747 is a medium-severity flaw (CVSS 4.3) affecting retty, retty. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Improper authorization in handler for custom URL scheme vulnerability in Retty App for Android versions prior to 4.8.13 and Retty App for iOS versions prior to 4.11.14 allows a remote attacker to lead a user to access an arbitrary website via the vulnerable App.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	4.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.0% (top 37%)
CISA exploited list	No
Weakness	CWE-862
Published	2021-07-14
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2021-07-14 02:15 UTCPublished CVE record published
2026-06-17 03:34 UTCUpdated Record last modified

retty retty UPGRADE

Affected: < 4.8.13

Fixed in: 4.8.13

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 4.8.13 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade retty

Note

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

retty retty UPGRADE

Affected: < 4.11.14

Fixed in: 4.11.14

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 4.11.14 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade retty

Note

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

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-2021-20747?

retty: upgrade to 4.8.13; retty: upgrade to 4.11.14. Exact commands for each OS are on this page.

Is CVE-2021-20747 being exploited?

CVE-2021-20747 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-2021-20747 affect?

CVE-2021-20747 affects retty, retty. Severity is medium (CVSS 4.3). Improper authorization in handler for custom URL scheme vulnerability in Retty App for Android versions prior to 4.8.13 and Retty App for iOS versions prior to 4.11.14 allows a remote attacker to lead a user to access an arbitrary website v

How urgent is CVE-2021-20747?

Priority 31/100. No elevated risk signals yet.

Software pages

Android vulnerabilities · iOS vulnerabilities

Related CVEs

CVE-2021-20748 HIGH 7.5 UPGRADE UPGRADE Retty App for Android versions prior to 4.8.13 and Retty App for iOS versions prior to 4.11.14 uses a hard-cod

References

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