CVE-2021-3977Network attack vector

Authenticated stored script execution

Published Dec 24, 2021 · Updated Aug 3, 2024

Stored cross-site scripting in Invoice Ninja before 5.3.35 allows remote authenticated users to execute script in another user's browser. Public records do not identify the input field or rendering sink; the linked password-reset controller patch shows no escaping or sanitization change. Exploitation requires low-privileged access under the reviewed GitHub assessment and affects browser-session confidentiality and integrity.

CVSS severity6.5
Medium
EPSS probability0.59%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in Invoice Ninja before 5.3.35 allows remote authenticated users to execute script in another user's browser. Public records do not identify the input field or rendering sink; the linked password-reset controller patch shows no escaping or sanitization change. Exploitation requires low-privileged access under the reviewed GitHub assessment and affects browser-session confidentiality and integrity.

The record

CVE
CVE-2021-3977
Published
Dec 24, 2021
Updated
Aug 3, 2024
Vendor
Invoice Ninja
Product
Invoice Ninja
Classifications
CWE-79
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 24, 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

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Is a vulnerable build present?

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

  1. Affected versionversion=unspecified <v.5.33

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Invoice Ninja · Invoice Ninjaversion=unspecified <v.5.33

Published CVSS scores

6.5huntr.devCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

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
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Public exploit references

No public exploit references are available in this record.

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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