CVE-2026-93640
HIGH 7.8A local privilege escalation vulnerability in the optional dnscache package of Zimbra Collaboration Suite (ZCS) allows the Unix zimbra account to access files with root privileges. The passwordless sudo policy permits arbitrary arguments to zmunbound, whose wrapper forwards them to Unbound without restricting the configuration path. An attacker can supply a configuration that retains root privileges and disables the chroot. Include directives expose root-readable file contents through parser errors, while an attacker-selected logfile path creates a root-owned file or appends Unbound log records to an existing file. This can disclose password hashes and private keys and corrupt privileged configuration files, preventing affected services from starting with the modified configuration. The affected configuration is present in ZCS 10.1.16 and 10.1.21 dnscache packages.
Severe if exploited (CVSS 7.8), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.1%chance of exploitation in 30 days · 2nd percentile
Impact if exploited
7.8CVSS 3.1 · HIGH
- ConfidentialityHigh
- IntegrityHigh
- AvailabilityHigh
What an attacker needs
- ⚠Access: Requires local access to the host
- ⚠Privileges: Requires a low-privilege account
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept
No public PoC is currently catalogued.
Search for new PoCs
Search GitHub now — results may be empty or unverified.
Tracked sources are checked daily for recent CVEs, including PoCs published after the original disclosure. A later release appears after a tracked source lists it and a refresh succeeds.
Data snapshot:
Weakness (CWE)
- CWE-732: Incorrect Permission Assignment for Critical Resource
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References and research data (JSON)
All CVSS metrics
- HIGH 7.8 v3.1 · CNA Primary
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - HIGH 7.8 v3.1 · NVD Secondary
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
Advisories
- https://wiki.zimbra.com/wiki/Zimbra_Security_Advisories CVE record · rapid7 · Updated 2026-10-23T13:34:41.851Z
NVD · CVE-2026-93640 · Updated 2026-10-24T04:18:27.440 - https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-108984 EUVD · EUVD-2026-108984
Technical & other
- https://www.rapid7.com/blog/post/ve-breaking-zimbra-identity-boundaries-part-1/ CVE record · rapid7 · Updated 2026-10-23T13:34:41.851Z
NVD · CVE-2026-93640 · Updated 2026-10-24T04:18:27.440