CVE-2021-21796: An exploitable use-after-free vulnerability exists in the JavaScript implementation of Nitro Pro PDF

This week

HIGH 7.8DOWNGRADE

CVE-2021-21796 is a high-severity flaw (CVSS 7.8) affecting nitro pro. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An exploitable use-after-free vulnerability exists in the JavaScript implementation of Nitro Pro PDF. A specially crafted document can cause an object containing the path to a document to be destroyed and then later reused, resulting in a use-after-free vulnerability, which can lead to code execution under the context of the application. An attacker can convince a user to open a document to trigger this vulnerability.

Why this priority

High severity
EPSS top 3%: very likely to be exploited
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	15.8% (top 3%)
CISA exploited list	No
Weakness	CWE-416
Published	2021-10-18
Last modified	2026-06-17

Publisher (CNA): Talos · Vendor: gonitro

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

Am I affected?

Timeline

2021-10-18 13:15 UTCPublished CVE record published
2026-06-17 03:36 UTCUpdated Record last modified

gonitro nitro pro DOWNGRADE

Affected: 13.31.0.605 · 13.33.2.645

Fixed in: no fixed release known

Safe to downgrade to: a release before 13.31.0.605

1. Check installed version

apt-cache policy nitro-pro || rpm -q nitro-pro || nitro-pro --version

2. No fixed release: DOWNGRADE to a release before 13.31.0.605 (Debian / Ubuntu)

apt-cache madison nitro-pro sudo apt install nitro-pro=<VERSION_BEFORE_13.31.0.605> sudo apt-mark hold nitro-pro

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list nitro-pro sudo dnf downgrade nitro-pro-<VERSION_BEFORE_13.31.0.605> sudo dnf versionlock add nitro-pro

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-2021-21796?

nitro pro: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-21796 being exploited?

CVE-2021-21796 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-2021-21796 affect?

CVE-2021-21796 affects nitro pro. Severity is high (CVSS 7.8). An exploitable use-after-free vulnerability exists in the JavaScript implementation of Nitro Pro PDF. A specially crafted document can cause an object containing the path to a document to be destroyed and then later reused, resulting in a u

How urgent is CVE-2021-21796?

Priority 57/100. High severity; EPSS top 3%: very likely to be exploited; Public exploit reference

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References

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