CVE-2021-43805Public exploitNetwork attack vector

Checkout denial of service via email regex backtracking

Published Dec 7, 2021 · Updated Aug 4, 2024

ReDoS in Solidus before 2.11.13, 3.0.0 through 3.0.3, and 3.1.0 through 3.1.3 allows remote attackers to hang guest checkout requests. Spree::EmailValidator::EMAIL_REGEXP ambiguously matches repeated a. fragments, forcing exponentially many backtracking paths when a trailing @ makes validation fail. Guest checkout requires no account; longer crafted addresses occupy a server process long enough to exhaust application resources.

CVSS severity7.5
High
EPSS probability1.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

ReDoS in Solidus before 2.11.13, 3.0.0 through 3.0.3, and 3.1.0 through 3.1.3 allows remote attackers to hang guest checkout requests. Spree::EmailValidator::EMAIL_REGEXP ambiguously matches repeated a. fragments, forcing exponentially many backtracking paths when a trailing @ makes validation fail. Guest checkout requires no account; longer crafted addresses occupy a server process long enough to exhaust application resources.

The record

CVE
CVE-2021-43805
Published
Dec 7, 2021
Updated
Aug 4, 2024
Vendor
Solidus
Product
Solidus
Classifications
CWE-1333, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=< 2.11.13
  2. Affected versionversion=>= 3.0.0, < 3.0.4
  3. Affected versionversion=>= 3.1.0, < 3.1.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Solidus · Solidusversion=< 2.11.13; version=>= 3.0.0, < 3.0.4; version=>= 3.1.0, < 3.1.4

Published CVSS scores

7.5NISTAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5GitLab Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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-1333Inefficient Regular Expression Complexity
T1499.003Application Exhaustion Flood

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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