CVE-2020-24837: An integer underflow has been found in the latest version of ZCFees

This month

HIGH 7.5REMOTEMITIGATE

CVE-2020-24837 is a high-severity flaw (CVSS 7.5) affecting zcfees. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An integer underflow has been found in the latest version of ZCFees. The variables 'currPeriodIdx' and 'lastPeriodExecIdx' are both unsigned integers, and the result of the minus operation may be a negative integer which leads to an underflow. The attackers can modify the current timestamp of the transaction somehow and block the execution of the process function.

Why this priority

High severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.6% (top 25%)
CISA exploited list	No
Weakness	CWE-191
Published	2021-02-10
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: zcfees project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-02-10 16:15 UTCPublished CVE record published
2026-06-17 03:06 UTCUpdated Record last modified

zcfees project zcfees MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy zcfees || rpm -q zcfees || zcfees --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-24837?

zcfees: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-24837 being exploited?

CVE-2020-24837 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-24837 affect?

CVE-2020-24837 affects zcfees. Severity is high (CVSS 7.5). An integer underflow has been found in the latest version of ZCFees. The variables 'currPeriodIdx' and 'lastPeriodExecIdx' are both unsigned integers, and the result of the minus operation may be a negative integer which leads to an underfl

How urgent is CVE-2020-24837?

Priority 50/100. High severity; Remotely exploitable, no login, no user action

References

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