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CVE-2019-25634

4mhz Base64 Decoder buffer overflow

8.4 HIGHPublic exploitEPSS 0.26%
  1. Published24 Mar 2026

Description

Base64 Decoder 1.1.2 contains a stack-based buffer overflow vulnerability that allows local attackers to execute arbitrary code by triggering a structured exception handler (SEH) overwrite. Attackers can craft a malicious input file that overflows a buffer, overwrites the SEH chain with a POP-POP-RET gadget address, and uses an egghunter payload to locate and execute shellcode for code execution.

CVSS 3.1 breakdown

Attack vectorLocal
Attack complexityLow
Privileges requiredNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

4mhz Base64 Decoder1.1.2

Remediation

No fixed version is recorded in the NVD data. Check the vendor advisory for the latest guidance.

References

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Frequently asked

Is CVE-2019-25634 being actively exploited?

CVE-2019-25634 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.26%.

How severe is CVE-2019-25634?

CVE-2019-25634 has a CVSS 3.1 base score of 8.4, rated high. EPSS estimates a 0.26% probability of exploitation.

Which products are affected by CVE-2019-25634?

Affected products include 4mhz Base64 Decoder.

How do I fix CVE-2019-25634?

Apply the vendor's patch or advisory guidance, then verify no affected versions remain across your devices.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2019-25634 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.