CVE-2021-41987Known exploitationPublic exploitNetwork attack vector

Unauthenticated code execution via Base64 length miscalculation

Published Mar 16, 2022 · Updated Aug 4, 2024

Heap-based buffer overflow in MikroTik RouterOS 6.46.8, 6.47.9, and 6.47.10 allows remote attackers to execute code via SCEP. ScepRequest::parseRequest calculates the Base64 output buffer as three times the input length divided by four, underallocating for malformed data and overwriting the heap. Exploitation requires an enabled SCEP server and knowledge of its scep_server_name path; successful shellcode can delete user data, reboot the device, and enable passwordless administrator access.

CVSS severity8.1
High
EPSS probability16.23%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in MikroTik RouterOS 6.46.8, 6.47.9, and 6.47.10 allows remote attackers to execute code via SCEP. ScepRequest::parseRequest calculates the Base64 output buffer as three times the input length divided by four, underallocating for malformed data and overwriting the heap. Exploitation requires an enabled SCEP server and knowledge of its scep_server_name path; successful shellcode can delete user data, reboot the device, and enable passwordless administrator access.

The record

CVE
CVE-2021-41987
Published
Mar 16, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 11, 2021Exploitation reportedHuapi exploit infrastructure
  2. Mar 16, 2022CVE publishedPublication date reported by the CVE source.
  3. 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P
8.1NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/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 exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1190Exploit Public-Facing Application

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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