CVE-2026-27750

CVE-2026-27750 is a high-severity vulnerability in Avira Internet Security with a CVSS 3.x base score of 7.8. 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-367.

Key facts

Description

Avira Internet Security contains a time-of-check time-of-use (TOCTOU) vulnerability in the Optimizer component. A privileged service running as SYSTEM identifies directories for cleanup during a scan phase and subsequently deletes them during a separate cleanup phase without revalidating the target path. A local attacker can replace a previously scanned directory with a junction or reparse point before deletion occurs, causing the privileged process to delete an unintended system location. This may result in deletion of protected files or directories and can lead to local privilege escalation, denial of service, or system integrity compromise depending on the affected target.

Frequently asked questions

What is CVE-2026-27750?
Avira Internet Security contains a time-of-check time-of-use (TOCTOU) vulnerability in the Optimizer component. A privileged service running as SYSTEM identifies directories for cleanup during a scan phase and subsequently deletes them during a separate cleanup phase without revalidating the target path. A local attacker can replace a previously scanned directory with a junction or reparse point before deletion occurs, causing the privileged process to delete an unintended system location. This may result in deletion of protected files or directories and can lead to local privilege escalation, denial of service, or system integrity compromise depending on the affected target.
How severe is CVE-2026-27750?
CVE-2026-27750 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-27750 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (1st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-27750?
CVE-2026-27750 affects Avira Internet Security. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-27750?
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.
Does CVE-2026-27750 have an EU (EUVD) identifier?
Yes. CVE-2026-27750 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-9822.
When was CVE-2026-27750 published?
CVE-2026-27750 was published on 2026-03-05 and last updated on 2026-06-17.

References

Affected products (1)

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