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CVE-2025-42599

From Exploited flaws, HARD’s guide to the flaws being used in attacks · Checked
This article is about a flaw in Qualitia Active! Mail. For every flaw being used in attacks, see Exploited flaws.

CVE-2025-42599 is a security flaw in Qualitia Active! Mail. Attackers can run their own code on Qualitia Active! Mail from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 28 Apr 2025.[1]

Qualitia Active! Mail is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Qualitia has published a fix or advice.

Description

CISA calls it a stack-based buffer overflow in Qualitia Active! Mail. In its words: “Qualitia Active! Mail contains a stack-based buffer overflow vulnerability that allows a remote, unauthenticated attacker to execute arbitrary or trigger a denial-of-service via a specially crafted request.”[1]

The CVE record adds: “Active! mail 6 BuildInfo: 6.60.05008561 and earlier contains a stack-based buffer overflow vulnerability. Receiving a specially crafted request created and sent by a remote unauthenticated attacker may lead to arbitrary code execution and/or a denial-of-service (DoS) condition.”[2]

The underlying weakness is stack buffer overflow (CWE-121), in MITRE’s list of common software weaknesses.

It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]

Affected versions

NVD’s record doesn’t list version ranges for it; Qualitia’s advisory has them[3]. CISA names the product as Qualitia Active! Mail.

Most families won’t have Qualitia Active! Mail; it’s for whoever looks after IT at work.

Exploitation

CISA added it to its catalog of known exploited vulnerabilities on 28 Apr 2025, 10 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 19 May 2025 to fix it.[1]

FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 3%. That’s in the top 12% of the flaws it scores.[4]

CISA assesses it as automatable: attackers can run it against many targets at once.

CISA doesn’t say who was attacked, or how.

Fix

Qualitia has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.”[1]

  1. Check whether you use it.Qualitia Active! Mail is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
  2. Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 19 May 2025 to fix it.
  3. If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.

You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.

Timeline

DateEvent
The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2]
CISA adds it to its catalog of flaws known to be used in attacks.[1]
CISA’s deadline for US government agencies to fix it.[1]
FIRST puts the odds of it being used in attacks in the next 30 days at 3%.[4]

See also

Other stack buffer overflow flaws

  • CVE-2026-7273, Zyxel GS1900 Series Switches: stack-based buffer overflow ·
  • CVE-2021-27137, DD-WRT: stack-based buffer overflow ·
  • CVE-2025-53521, F5 BIG-IP: stack-based buffer overflow ·
  • CVE-2025-20352, Cisco IOS and IOS XE: software SNMP denial of service and remote code execution ·
  • CVE-2025-22457, Ivanti Connect Secure, Policy Secure, and ZTA Gateways: stack-based buffer overflow ·

Added the same day

  • CVE-2025-3928, Commvault Web Server: unspecified ·
  • CVE-2025-1976, Broadcom Brocade Fabric OS: code injection ·

References

  1. ^ Cybersecurity and Infrastructure Security Agency. “Qualitia Active! Mail Stack-Based Buffer Overflow Vulnerability”. Known Exploited Vulnerabilities Catalog, added 28 Apr 2025.
  2. ^ National Institute of Standards and Technology. “CVE-2025-42599 Detail”. National Vulnerability Database, published 18 Apr 2025.
  3. ^ Qualitia. Advisories and fixes: qualitia.com.
  4. ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.034, percentile 88.7, 31 Oct 2026.
  5. CVE Program. “CVE-2025-42599”. The official CVE record.

This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.