Threat Intelligence / CVE / CVE-2025-52691

CVE-2025-52691 — Smartertools Smartermail

CISA KEV

CVSS v3.1 10 (CRITICAL) · EPSS 87.2% (higher than 99.4% of all scored CVEs) · Priority 9/10 · Published 2025-12-29

As of 2026-01-27, CVE-2025-52691 is a CRITICAL-severity vulnerability in Smartertools Smartermail, CVSS v3.1 10, EPSS 87.2% (99.4th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-01-26), with a US federal remediation deadline of 2026-02-16. Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2025-52691, most recently “Storm-1175 Medusa Ransomware Zero-Day Exploitation Campaign (CVE-2026-23760, CVE-2025-10035)”.

Last updated: 2026-01-27

What is CVE-2025-52691?

Successful exploitation of the vulnerability could allow an unauthenticated attacker to upload arbitrary files to any location on the mail server, potentially enabling remote code execution.

The record classifies CVE-2025-52691 under weakness class CWE-434. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 258 days ago.

Severity and exploitation probability

CVSS v3.1 base score: 10 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
EPSS (FIRST): 87.2% probability of exploitation in the next 30 days, higher than 99.4% of all scored CVEs
CISA KEV: Listed since 2026-01-26, federal remediation deadline 2026-02-16
Threadlinqs priority: 9/10 — CISA KEV-listed, which Threadlinqs floors at 9
Published: 2025-12-29, last modified 2026-01-27

Is CVE-2025-52691 being exploited?

CISA added CVE-2025-52691 to the Known Exploited Vulnerabilities catalog on 2026-01-26, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2026-02-16 under BOD 22-01. It currently carries a trending score of 40 in the Threadlinqs vulnerability feed.

Affected products and versions

Smartertools: Smartermail

How to fix CVE-2025-52691

The record marks a vendor fix as available for CVE-2025-52691. Patch reference: https://www.zimbra.com/security-advisories/cve-2025-52691/. Because CVE-2025-52691 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2026-02-16. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2025-52691

1 tracked threat in the Threadlinqs corpus references CVE-2025-52691, either in the campaign’s CVE list or as an indicator on the campaign record.

Storm-1175 Medusa Ransomware Zero-Day Exploitation Campaign (CVE-2026-23760, CVE-2025-10035) — CRITICAL · 2026-04-06

Sources

Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

Full detection coverage & IOCs for threats exploiting CVE-2025-52691 are available via the Threadlinqs MCP server (Purple tier). View plans →

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