CVE-2026-25039
UNC workspace name leads to SMB mount, NTLM hash exposure and app hang
Is CVE-2026-25039 being exploited?
Not confirmed. CVE-2026-25039 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.55% probability of exploitation in the next 30 days.
How severe is CVE-2026-25039?
CVE-2026-25039 is rated High with a CVSS score of 8.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-25039?
Yes. A fix has been recorded for CVE-2026-25039. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-25039 affect?
CVE-2026-25039 affects Parsec (Windows client), Windows filesystem mountpoints for Parsec workspaces. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-25039?
Block outbound SMB (TCP 445), disallow UNC workspace names, apply vendor patch when released
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Attacker-supplied UNC causes client to mount attacker SMB share, exposing NTLM hashes (credential theft) and enabling lateral movement; app may hang if UNC unreachable.
Immediate action required
- affected< 3.3.3-rc.0
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.