CVE-2021-20728: Improper access control vulnerability in goo blog App for Android ver.1.2.25 and earlier and for iOS ver.1.3.3

Q: How do I fix CVE-2021-20728?

goo blog: upgrade to newer than 1.2.25; goo blog: upgrade to newer than 1.3.3. Exact commands for each OS are on this page.

Q: Is CVE-2021-20728 being exploited?

CVE-2021-20728 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-2021-20728 affect?

CVE-2021-20728 affects goo blog, goo blog. Severity is medium (CVSS 5.3). Improper access control vulnerability in goo blog App for Android ver.1.2.25 and earlier and for iOS ver.1.3.3 and earlier allows a remote attacker to lead a user to access an arbitrary website via the vulnerable App.

Q: How urgent is CVE-2021-20728?

Priority 39/100. Remotely exploitable, no login, no user action

Routine

MEDIUM 5.3REMOTEUPGRADEUPGRADE

CVE-2021-20728 is a medium-severity flaw (CVSS 5.3) affecting goo blog, goo blog. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Improper access control vulnerability in goo blog App for Android ver.1.2.25 and earlier and for iOS ver.1.3.3 and earlier allows a remote attacker to lead a user to access an arbitrary website via the vulnerable App.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.0% (top 37%)
CISA exploited list	No
Published	2021-06-09
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2021-06-09 02:15 UTCPublished CVE record published
2026-06-17 03:34 UTCUpdated Record last modified

nttr goo blog UPGRADE

Affected: <= 1.2.25

Fixed in: newer than 1.2.25

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy goo-blog || rpm -q goo-blog || goo-blog --version

2. UPGRADE to newer than 1.2.25 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade goo-blog

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade goo-blog

Note

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

nttr goo blog UPGRADE

Affected: <= 1.3.3

Fixed in: newer than 1.3.3

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy goo-blog || rpm -q goo-blog || goo-blog --version

2. UPGRADE to newer than 1.3.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade goo-blog

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade goo-blog

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-2021-20728?

goo blog: upgrade to newer than 1.2.25; goo blog: upgrade to newer than 1.3.3. Exact commands for each OS are on this page.

Is CVE-2021-20728 being exploited?

CVE-2021-20728 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-2021-20728 affect?

CVE-2021-20728 affects goo blog, goo blog. Severity is medium (CVSS 5.3). Improper access control vulnerability in goo blog App for Android ver.1.2.25 and earlier and for iOS ver.1.3.3 and earlier allows a remote attacker to lead a user to access an arbitrary website via the vulnerable App.

How urgent is CVE-2021-20728?

Priority 39/100. Remotely exploitable, no login, no user action

Software pages

Android vulnerabilities · iOS vulnerabilities

Related CVEs

CVE-2022-25420 CRITICAL 9.8 DOWNGRADE NTT Resonant Incorporated goo blog App Web Application 1.0 is vulnerable to CLRF injection

References

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