CVE-2021-20721: KonaWiki2 versions prior to 2.2.4 allows a remote attacker to upload arbitrary files via unspecified vectors

Q: How do I fix CVE-2021-20721?

konawiki: upgrade to 2.2.4. Exact commands for each OS are on this page.

Q: Is CVE-2021-20721 being exploited?

CVE-2021-20721 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-2021-20721 affect?

CVE-2021-20721 affects konawiki. Severity is critical (CVSS 9.8). KonaWiki2 versions prior to 2.2.4 allows a remote attacker to upload arbitrary files via unspecified vectors. If the file contains PHP scripts, arbitrary code may be executed.

Q: How urgent is CVE-2021-20721?

Priority 58/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 9.8REMOTEUPGRADE

CVE-2021-20721 is a critical-severity flaw (CVSS 9.8) affecting konawiki. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

KonaWiki2 versions prior to 2.2.4 allows a remote attacker to upload arbitrary files via unspecified vectors. If the file contains PHP scripts, arbitrary code may be executed.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.5% (top 25%)
CISA exploited list	No
Weakness	CWE-434
Published	2021-05-20
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2021-05-20 02:15 UTCPublished CVE record published
2026-06-17 03:34 UTCUpdated Record last modified

kujirahand konawiki UPGRADE

Affected: < 2.2.4

Fixed in: 2.2.4

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 2.2.4 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade konawiki

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-2021-20721?

konawiki: upgrade to 2.2.4. Exact commands for each OS are on this page.

Is CVE-2021-20721 being exploited?

CVE-2021-20721 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-2021-20721 affect?

CVE-2021-20721 affects konawiki. Severity is critical (CVSS 9.8). KonaWiki2 versions prior to 2.2.4 allows a remote attacker to upload arbitrary files via unspecified vectors. If the file contains PHP scripts, arbitrary code may be executed.

How urgent is CVE-2021-20721?

Priority 58/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

PHP vulnerabilities

Related CVEs

CVE-2021-20720 CRITICAL 9.8 UPGRADE SQL injection vulnerability in the KonaWiki2 versions prior to 2.2.4 allows remote attackers to execute arbitr
CVE-2020-5614 MEDIUM 5.3 UPGRADE Directory traversal vulnerability in KonaWiki 3.1.0 and earlier allows remote attackers to read arbitrary file
CVE-2020-5613 MEDIUM 6.1 UPGRADE Cross-site scripting vulnerability in KonaWiki 3.1.0 and earlier allows remote attackers to execute an arbitra
CVE-2020-5612 MEDIUM 6.1 UPGRADE Cross-site scripting vulnerability in KonaWiki 2.2.0 and earlier allows remote attackers to execute an arbitra

References

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