CVE-2021-21798Public exploitNetwork attack vector

Code execution via stale JavaScript stack frame

Published Sep 15, 2021 · Updated Aug 3, 2024

Code execution in Nitro Pro 13.31.0.605 and 13.33.2.645 allows context-dependent attackers to run code via a crafted PDF. An exception in document.flattenPages skips restoration of JSContext.fp, leaving it pointing to an out-of-scope JSStackFrame that is later dereferenced. A user must open a malicious PDF with JavaScript enabled; successful exploitation runs code in the application's context.

CVSS severity8.8
High
EPSS probability16.03%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Code execution in Nitro Pro 13.31.0.605 and 13.33.2.645 allows context-dependent attackers to run code via a crafted PDF. An exception in document.flattenPages skips restoration of JSContext.fp, leaving it pointing to an out-of-scope JSStackFrame that is later dereferenced. A user must open a malicious PDF with JavaScript enabled; successful exploitation runs code in the application's context.

The record

CVE
CVE-2021-21798
Published
Sep 15, 2021
Updated
Aug 3, 2024
Vendor
Nitro Software, Inc.
Product
Nitro Pro
Classifications
CWE-562, T1204.002, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 15, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Nitro Pro 13.31.0.605 , Nitro Pro 13.33.2.645

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nitro Software, Inc. · Nitro Proversion=Nitro Pro 13.31.0.605 , Nitro Pro 13.33.2.645

Published CVSS scores

8.8Cisco TalosCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-562Return of Stack Variable Address
T1204.002Malicious File
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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