How severe is CVE-2025-52691?

CVE-2025-52691 has a CVSS score of 10/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2025-52691?

Affected package information for CVE-2025-52691 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2025-52691?

No fixed version has been published for CVE-2025-52691 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2025-52691 actively exploited in the wild?

Yes. There are 5 known exploit references for CVE-2025-52691, including . All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2025-52691?

CVE-2025-52691 has an EPSS (Exploit Prediction Scoring System) score of 89.1%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2025-52691 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2025-52691 (SmarterTools SmarterMail Unrestricted Upload of File with Dangerous Type Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-01-26. CISA required all US federal civilian agencies to remediate this vulnerability by 2026-02-16. The required action was: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. This CVE has been used in known ransomware campaigns. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2025-52691?

CVE-2025-52691 is classified as Unrestricted File Upload (CWE-434). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Which products and versions are affected by CVE-2025-52691?

CVE-2025-52691 affects smartertools smartermail. Check the affected-products list on this page against your deployed version to confirm exposure.

Is there exploit tooling available for CVE-2025-52691?

A Nuclei detection template exists for CVE-2025-52691, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2025-52691 published, and has it been updated?

CVE-2025-52691 was published on December 29, 2025 and was last updated on January 27, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2026-01-26 — agencies required to remediate by 2026-02-16 · Ransomware

CVE-2025-52691

CRITICAL

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.

Published

Dec 29, 2025

Updated

Jan 27, 2026

Affected

0 pkgs

Patched

None yet

Exploits

5 known

EPSS Exploitation Probability

via FIRST.org ↗

89.1%probability of exploitation in next 30 days

Very High Risk100th percentile-1.04%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

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.

Affected Products

1 product · 1 configurations

Application

smartermailsmartertools

< 100.0.9413

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

rxerium/CVE-2025-52691

Detection for CVE-2025-52691

⭐ 19🍴 4Feb 2026

watchtowrlabs/watchTowr-vs-SmarterMail-CVE-2025-52691

⭐ 19🍴 3May 2026

DeathShotXD/CVE-2025-52691-APT-PoC

An enhanced proof-of-concept exploit for CVE-2025-52691 (SmarterMail Arb

⭐ 3🍴 3Apr 2026

yt2w/CVE-2025-52691

⭐ 3🍴 1May 2026

rimbadirgantara/CVE-2025-52691-poc

⭐ 3🍴 0May 2026

Frequently Asked Questions

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.

O3 Security · Impact-Aware SCA

Is CVE-2025-52691 in your stack?

O3 detects CVE-2025-52691 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my stack How O3 SCA works