CVE-2021-20105Public exploitNetwork attack vector

Open redirect via unvalidated ref parameter

Published Jun 29, 2021 · Updated Aug 3, 2024

Open redirect in Safari_init.php in MachForm before 16 allows remote attackers to redirect browsers via a crafted ref parameter. The script Base64-decodes ref, applies HTML entity encoding that does not restrict destinations, and passes the result directly into the Location response header. Exploitation requires a user to follow the crafted link, after which the trusted MachForm origin redirects the browser to an attacker-chosen page for phishing.

CVSS severity6.1
Medium
EPSS probability0.74%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Open redirect in Safari_init.php in MachForm before 16 allows remote attackers to redirect browsers via a crafted ref parameter. The script Base64-decodes ref, applies HTML entity encoding that does not restrict destinations, and passes the result directly into the Location response header. Exploitation requires a user to follow the crafted link, after which the trusted MachForm origin redirects the browser to an attacker-chosen page for phishing.

The record

CVE
CVE-2021-20105
Published
Jun 29, 2021
Updated
Aug 3, 2024
Vendor
Laymance Technologies LLC
Product
MachForm
Classifications
CWE-601, T1566.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 29, 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=All versions prior to version 16

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Laymance Technologies LLC · MachFormversion=All versions prior to version 16

Published CVSS scores

5.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.7TenableCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:N/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 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-601URL Redirection to Untrusted Site ('Open Redirect')
T1566.002Spearphishing Link

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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