CVE-2024-39921Network attack vector

Partial traffic decryption via RSA timing discrepancy

Published Sep 4, 2024 · Updated Mar 13, 2025

Observable timing discrepancy in affected IPCOM EX2 and VE2 firmware allows remote attackers to decrypt portions of encrypted traffic. The SSL accelerator and SSL-VPN functions perform RSA key exchange with observable processing-time differences. Exploitation requires access to the encrypted communication and its timing behavior; the specific cryptographic operation causing the discrepancy is undisclosed.

CVSS severity5.9
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Observable timing discrepancy in affected IPCOM EX2 and VE2 firmware allows remote attackers to decrypt portions of encrypted traffic. The SSL accelerator and SSL-VPN functions perform RSA key exchange with observable processing-time differences. Exploitation requires access to the encrypted communication and its timing behavior; the specific cryptographic operation causing the discrepancy is undisclosed.

The record

CVE
CVE-2024-39921
Published
Sep 4, 2024
Updated
Mar 13, 2025
Vendor
Fsas Technologies
Product
IPCOM VE2 Series
Classifications
CWE-203, CWE-208
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 4, 2024CVE publishedPublication date reported by the CVE source.
  2. Mar 13, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=V01L04NF0001 to V01L06NF0112

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Fsas Technologies · IPCOM VE2 Seriesversion=V01L04NF0001 to V01L06NF0112
Fsas Technologies · IPCOM EX2 Seriesversion=V01L02NF0001 to V01L06NF0401; version=V01L20NF0001 to V01L20NF0401; version=V02L20NF0001 to V02L21NF0301

Published CVSS scores

5.9JPCERT/CC and IPACVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
7.5CISA ADP VulnrichmentCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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 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 exploitUnconfirmed

Weakness, pattern, technique

CWE-203Observable Discrepancy
CWE-208Observable Timing Discrepancy

Public exploit references

No public exploit references are available in this record.

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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