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GHSA-3w5p-95mh-gq75
No affected components available
Impact
A denial-of-service (DoS) vulnerability exists in the factorial operator implementation of NCalc. Specially crafted expressions containing extremely large factorial operands can trigger excessive CPU consumption or cause evaluation to enter a non-terminating loop due to integer overflow in the factorial calculation logic.
Applications that evaluate untrusted expressions using affected versions of NCalc may be vulnerable to resource exhaustion, potentially resulting in service disruption or application unresponsiveness.
This issue can be triggered with expressions such as:
99999999999999!
9223372036854775807!
1.5e16!
Patches
The vulnerability has been fixed by adding bounds validation for factorial operands and rejecting unsupported values before evaluation.
Users should upgrade to the first release containing the fix from pull request #575. (v6.1.1+)
Workarounds
If upgrading is not immediately possible:
- Do not evaluate expressions originating from untrusted users.
- Validate or sanitize expressions before evaluation and reject factorial operations on large values.
- Implement execution time limits, request timeouts, or cancellation mechanisms around expression evaluation.
These mitigations may reduce exposure but do not fully address the underlying vulnerability.
The vulnerability can be exploited over a local network, such as Wi-Fi. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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