CVE-2021-26605: An improper input validation vulnerability in the service of ezPDFReader allows attacker to execute arbitrary

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HIGH 7.5REMOTEUPGRADE

CVE-2021-26605 is a high-severity flaw (CVSS 7.5) affecting ezpdfreader. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An improper input validation vulnerability in the service of ezPDFReader allows attacker to execute arbitrary command. This issue occurred when the ezPDF launcher received and executed crafted input values through JSON-RPC communication.

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.0% (top 36%)
CISA exploited list	No
Weakness	CWE-20
Published	2021-08-05
Last modified	2026-06-17

Publisher (CNA): KrCERT/CC · Vendor: unidocs

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

Am I affected?

Timeline

2021-08-05 21:15 UTCPublished CVE record published
2026-06-17 03:43 UTCUpdated Record last modified

unidocs ezpdfreader UPGRADE

Affected: >= 2.0 and <= 3.0

Fixed in: newer than 3.0

Safe to downgrade to: a release before 2.0

1. Check installed version

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

2. UPGRADE to newer than 3.0 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ezpdfreader

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 2.0 (Debian / Ubuntu)

apt-cache madison ezpdfreader sudo apt install ezpdfreader=<VERSION_BEFORE_2.0> sudo apt-mark hold ezpdfreader

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

dnf --showduplicates list ezpdfreader sudo dnf downgrade ezpdfreader-<VERSION_BEFORE_2.0> sudo dnf versionlock add ezpdfreader

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-2021-26605?

ezpdfreader: upgrade to newer than 3.0. Exact commands for each OS are on this page.

Is CVE-2021-26605 being exploited?

CVE-2021-26605 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-2021-26605 affect?

CVE-2021-26605 affects ezpdfreader. Severity is high (CVSS 7.5). An improper input validation vulnerability in the service of ezPDFReader allows attacker to execute arbitrary command. This issue occurred when the ezPDF launcher received and executed crafted input values through JSON-RPC communication.

How urgent is CVE-2021-26605?

Priority 47/100. High severity; Remotely exploitable, no login, no user action

References

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