What’s Vulnerable › Vulnerabilities

CVE-2019-20044

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-02-24 · updated 2026-06-17
• Weakness: CWE-273

Description

In Zsh before 5.8, attackers able to execute commands can regain privileges dropped by the --no-PRIVILEGED option. Zsh fails to overwrite the saved uid, so the original privileges can be restored by executing MODULE_PATH=/dir/with/module zmodload with a module that calls setuid().

Affected products

• Apple iPadOS: before 13.5 — fixed in 13.5
• Apple Iphone Os: before 13.5 — fixed in 13.5
• macOS: before 10.15.5; from 10.13.0 before 10.13.6; from 10.14.0 before 10.14.6; from 10.15 before 10.15.5; 10.13.6, 10.13.6-security_update_2018-002, 10.13.6-security_update_2018-003, 10.13.6-security_update_2019-001, 10.13.6-security_update_2019-002, 10.13.6-security_update_2019-003 (+15) — fixed in 10.13.6, 10.14.6, 10.15.5
• Apple tvOS: before 13.4.5 — fixed in 13.4.5
• Apple watchOS: before 6.2.5 — fixed in 6.2.5
• Debian Linux: 8.0, 9.0
• Fedoraproject Fedora: 30, 31
• zsh: before 5.8 — fixed in 5.8

How to fix

Upgrade to a fixed version: Apple iPadOS 13.5; Apple Iphone Os 13.5; macOS 10.13.6, 10.14.6, 10.15.5; Apple tvOS 13.4.5; Apple watchOS 6.2.5; zsh 5.8. Check the vendor advisory for mitigations.

References

• http://seclists.org/fulldisclosure/2020/May/49
• http://seclists.org/fulldisclosure/2020/May/53
• http://seclists.org/fulldisclosure/2020/May/55
• http://seclists.org/fulldisclosure/2020/May/59
• http://zsh.sourceforge.net/releases.html
• https://github.com/XMB5/zsh-privileged-upgrade
• https://lists.debian.org/debian-lts-announce/2020/03/msg00004.html
• https://lists.debian.org/debian-lts-announce/2020/12/msg00000.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/FP64FFIZI2CKQOEAOI5A72PVQULE7ZZC/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PN5V7MPHRRP7QNHOEK56S7QGRU53WUN6/
• https://security.gentoo.org/glsa/202003-55
• https://support.apple.com/HT211168

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