CVE-2021-31864Network attack vector

Unauthorized issue-note creation via alternative permission check

Published Apr 28, 2021 · Updated Aug 3, 2024

Authorization bypass in Redmine 3.3.0 through 4.0.8, 4.1.0 through 4.1.2, and 4.2.0 allows remote authenticated users to add issue notes. MailHandler accepts either add_issue_notes or edit_issues when processing a reply instead of requiring the note-specific Issue#notes_addable? result. An incoming-email handler must be configured, and the sender needs edit_issues without add_issue_notes; exploitation writes an unauthorized note to an existing issue.

CVSS severity5.3
Medium
EPSS probability1.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in Redmine 3.3.0 through 4.0.8, 4.1.0 through 4.1.2, and 4.2.0 allows remote authenticated users to add issue notes. MailHandler accepts either add_issue_notes or edit_issues when processing a reply instead of requiring the note-specific Issue#notes_addable? result. An incoming-email handler must be configured, and the sender needs edit_issues without add_issue_notes; exploitation writes an unauthorized note to an existing issue.

The record

CVE
CVE-2021-31864
Published
Apr 28, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
Unavailable
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 28, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/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

No sourced classifications are available.

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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