CVE-2025-63685: Quark Cloud Drive v3.23.2 has a DLL Hijacking vulnerability

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2025-63685 is a critical-severity flaw (CVSS 9.8) affecting quark cloud drive. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Quark Cloud Drive v3.23.2 has a DLL Hijacking vulnerability. This vulnerability stems from the insecure loading of system libraries. Specifically, the application does not validate the path or signature of [regsvr32.exe] it loads. An attacker can place a crafted malicious DLL in the application's startup directory, which will be loaded and executed when the user launches the program.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 66%)
CISA exploited list	No
Weakness	CWE-491
Published	2025-11-20
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: quark

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-11-20 21:16 UTCPublished CVE record published
2026-06-17 09:53 UTCUpdated Record last modified

quark quark cloud drive DOWNGRADE

Affected: 3.23.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.23.2

1. Check installed version

apt-cache policy quark-cloud-drive || rpm -q quark-cloud-drive || quark-cloud-drive --version

2. No fixed release: DOWNGRADE to a release before 3.23.2 (Debian / Ubuntu)

apt-cache madison quark-cloud-drive sudo apt install quark-cloud-drive=<VERSION_BEFORE_3.23.2> sudo apt-mark hold quark-cloud-drive

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list quark-cloud-drive sudo dnf downgrade quark-cloud-drive-<VERSION_BEFORE_3.23.2> sudo dnf versionlock add quark-cloud-drive

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-63685?

quark cloud drive: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2025-63685 being exploited?

CVE-2025-63685 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-63685 affect?

CVE-2025-63685 affects quark cloud drive. Severity is critical (CVSS 9.8). Quark Cloud Drive v3.23.2 has a DLL Hijacking vulnerability. This vulnerability stems from the insecure loading of system libraries. Specifically, the application does not validate the path or signature of [regsvr32.exe] it loads. An attack

How urgent is CVE-2025-63685?

Priority 53/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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