CVE-2018-5731

CVE-2018-5731 is a high-severity vulnerability in Heimdalsecurity Heimdal with a CVSS 3.x base score of 7.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-20.

Key facts

Description

An issue was discovered in Heimdal PRO 2.2.190. As part of the scanning feature, a process called md.hs writes an executable called CS1.tmp to C:\windows\TEMP. Afterwards the executable is run. It is possible for an attacker to create the file first, let md.hs overwrite it, and then rewrite the file in the window between md.hs closing the file and executing it. This can be exploited via opportunistic locks and a high priority thread. The vulnerability is triggered when a scan starts. NOTE: any affected Heimdal products are completely unrelated to the Heimdal vendor of a Kerberos 5 product on the h5l.org web site.

Frequently asked questions

What is CVE-2018-5731?
An issue was discovered in Heimdal PRO 2.2.190. As part of the scanning feature, a process called md.hs writes an executable called CS1.tmp to C:\windows\TEMP. Afterwards the executable is run. It is possible for an attacker to create the file first, let md.hs overwrite it, and then rewrite the file in the window between md.hs closing the file and executing it. This can be exploited via opportunistic locks and a high priority thread. The vulnerability is triggered when a scan starts. NOTE: any affected Heimdal products are completely unrelated to the Heimdal vendor of a Kerberos 5 product on the h5l.org web site.
How severe is CVE-2018-5731?
CVE-2018-5731 has a CVSS 3.x base score of 7.0, rated high severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2018-5731 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-5731?
CVE-2018-5731 affects Heimdalsecurity Heimdal. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2018-5731?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-5731 published?
CVE-2018-5731 was published on 2018-03-22 and last updated on 2026-06-17.

References

Affected products (1)

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