CVE-2021-3728Public exploitNetwork attack vector

Budget-limit deletion via state-changing GET request

Published Aug 23, 2021 · Updated Aug 3, 2024

Cross-site request forgery in Firefly III 5.5.13 and earlier allows remote attackers to delete a victim's budget limits. The budget-limit deletion route accepts a state-changing GET request, so a crafted link invokes it without a CSRF token. A logged-in victim must follow the crafted request; successful exploitation deletes budget-limit data without exposing account contents.

CVSS severity6.5
Medium
EPSS probability0.50%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site request forgery in Firefly III 5.5.13 and earlier allows remote attackers to delete a victim's budget limits. The budget-limit deletion route accepts a state-changing GET request, so a crafted link invokes it without a CSRF token. A logged-in victim must follow the crafted request; successful exploitation deletes budget-limit data without exposing account contents.

The record

CVE
CVE-2021-3728
Published
Aug 23, 2021
Updated
Aug 3, 2024
Vendor
Firefly III
Product
Firefly III
Classifications
CWE-352, T1565
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 23, 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 <=5.5.13

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Firefly III · Firefly IIIversion=unspecified <=5.5.13

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
6.5huntr.dev CNACVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
4.3NIST NVDAV:N/AC:M/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-352Cross-Site Request Forgery (CSRF)
T1565Data Manipulation

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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