返回 CVE 瀏覽器

CVE-2021-3493

🔥 Known Exploited (CISA KEV)HIGH

8.8

CVSS Severity Score

EPSS Score66.1960%

EPSS Percentile89.88th

Published2021-04-17

Last Modified2025-10-28

Data SourcesNVDCISA KEVFIRST.org EPSS

Vulnerability Description

The overlayfs implementation in the linux kernel did not properly validate with respect to user namespaces the setting of file capabilities on files in an underlying file system. Due to the combination of unprivileged user namespaces along with a patch carried in the Ubuntu kernel to allow unprivileged overlay mounts, an attacker could use this to gain elevated privileges.

Affected Platforms (CPE)

💻

Canonical

Ubuntu Linux

< 18.04>= 18.04.1 and < 20.04< 20.10

References & Advisories

🔗 http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1.html

🔗 http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.html

🔗 http://packetstormsecurity.com/files/165151/Ubuntu-Overlayfs-Local-Privilege-Escalation.html

🔗 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7c03e2cda4a584cadc398e8f6641ca9988a39d52

🔗 https://ubuntu.com/security/notices/USN-4917-1

🔗 https://www.openwall.com/lists/oss-security/2021/04/16/1

🔗 http://packetstormsecurity.com/files/162434/Kernel-Live-Patch-Security-Notice-LSN-0076-1.html

🔗 http://packetstormsecurity.com/files/162866/Ubuntu-OverlayFS-Local-Privilege-Escalation.html

相關資安分析文章

每日全球網絡威脅情報摘要｜2026 年 7 月 30 日

本期威脅情報聚焦 Ruby on Rails CVE-2026-66066 任意檔案讀取、Gitea CVE-2026-60004 Git Hook 命令執行、Minnesota 水務系統協調式攻擊、Ruflo MCP Bridge RCE，以及 Firefox CVE-2026-10702。

每日全球網絡威脅情報摘要｜2026 年 7 月 29 日

本期威脅情報聚焦遭主動利用的 Arista VeloCloud CVE-2026-16812、JetBrains TeamCity CVE-2026-63077 未驗證 RCE、公開 IPMI／BMC 的 RAKP 密碼風險，以及 Origin Energy 與 MCBS 資料外洩更新。

相關漏洞威脅

In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: Prevent UAF caused by non-leader exec() rac...

In the Linux kernel, the following vulnerability has been resolved: s390/pkey: Check length in PKEY_VERIFYPROTK ioctl Explicitly...

In the Linux kernel, the following vulnerability has been resolved: s390/pkey: Check length in pkey_pckmo handler implementation ...

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix use-after-free in l2cap_sock_new_connec...