CVE-2026-27750— Avira Internet Security Optimizer TOCTOU
Quick assessment
Affected
Gen Digital Inc. Avira Internet Security
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.
Avira Internet Security是德国Avira公司的一款网络安全防护软件。 Avira Internet Security存在安全漏洞，该漏洞源于Optimizer组件存在竞争条件，可能导致本地攻击者删除受保护文件或目录，进而引发本地权限提升、拒绝服务或系统完整性破坏。
Possible ATT&CK Techniques 3 AI
T1006 · Direct Volume Access T1485 · Data Destruction T1546.001 · Change Default File Association
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I. Basic Information for CVE-2026-27750
Vulnerability Information
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Vulnerability Title
Avira Internet Security Optimizer TOCTOU
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
检查时间与使用时间(TOCTOU)的竞争条件
Source: CVE Program / CVE List V5
Vulnerability Title
Avira Internet Security 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Avira Internet Security是德国Avira公司的一款网络安全防护软件。 Avira Internet Security存在安全漏洞，该漏洞源于Optimizer组件存在竞争条件，可能导致本地攻击者删除受保护文件或目录，进而引发本地权限提升、拒绝服务或系统完整性破坏。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
| Vendor | Product | Affected Versions | CPE | Subscribe |
|---|---|---|---|---|
| Gen Digital Inc. | Avira Internet Security | 0 ~ 1.1.109.1990 | - |
|
II. Public POCs for CVE-2026-27750
| # | POC Description | Source Link | Shenlong Link |
|---|
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Vendor Advisories for CVE-2026-27750 (1)
-
Avira Internet Security Optimizer TOCTOU | Advisories | VulnCheck third-party-advisory
Security Blog Posts for CVE-2026-27750 (1)
-
Avira: Deserialize, Delete and Escalate - The Proper Way to Use an AV - Quarkslab's blog technical-description exploit
Vendor Pages for CVE-2026-27750 (1)
Same Patch Batch · Gen Digital Inc. · 2026-03-05 · 3 CVEs total
| CVE-2026-27748 | 7.8 HIGH | Avira Internet Security Arbitrary File Deletion via Improper Link Resolution |
| CVE-2026-27749 | 7.8 HIGH | Avira Internet Security System Speedup Insecure Deserialization |
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V. Comments for CVE-2026-27750
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