CVE-2025-47812
CVE-2025-47812 is a security flaw in Wing FTP Server, software companies use to send and receive files. Attackers can run their own code on Wing FTP Server. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 14 Jul 2025.[1]
Wing FTP Server 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. Fixed in version 7.4.4 of Wing FTP Server.
Description
CISA calls it an improper neutralization of null byte or NUL character in Wing FTP Server Wing FTP Server. In its words: “Wing FTP Server contains an improper neutralization of null byte or NUL character vulnerability that can allow injection of arbitrary Lua code into user session files. This can be used to execute arbitrary system commands with the privileges of the FTP service (root or SYSTEM by default).”[1]
The CVE record adds: “In Wing FTP Server before 7.4.4. the user and admin web interfaces mishandle '\0' bytes, ultimately allowing injection of arbitrary Lua code into user session files. This can be used to execute arbitrary system commands with the privileges of the FTP service (root or SYSTEM by default). This is thus a remote code execution vulnerability that guarantees a total server compromise. This is also exploitable via anonymous FTP accounts.”[2]
The underlying weakness is CWE-158, in MITRE’s list of common software weaknesses.
It scores 10.0 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by the organisation that published the CVE using CVSS 3.1.[2]
Affected versions
NVD’s record lists one fixed version: everything before it is affected.[2]
| Product | Fixed in |
|---|---|
| Wing FTP Server | 7.4.4 |
Most families won’t have Wing FTP Server; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 14 Jul 2025, 4 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 4 Aug 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 94%. That’s in the top 1% 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
Wing FTP Server 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]
- Check whether you use it.Wing FTP Server 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.
- Send this page to your IT person.Ask them to confirm it’s fixed (fixed in version 7.4.4 of Wing FTP Server), or not in use. CISA gave US government agencies until 4 Aug 2025 to fix it.
- 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
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 10.0.[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 94%.[4] |
See also
Other Wing FTP Server flaws
- CVE-2025-47813: information disclosure ·
Similar flaws
- CVE-2009-1537, Microsoft DirectX: NULL byte overwrite ·
- CVE-2022-1040, Sophos Firewall: authentication bypass ·
References
- ^ Cybersecurity and Infrastructure Security Agency. “Wing FTP Server Improper Neutralization of Null Byte or NUL Character Vulnerability”. Known Exploited Vulnerabilities Catalog, added 14 Jul 2025.
- ^ National Institute of Standards and Technology. “CVE-2025-47812 Detail”. National Vulnerability Database, published 10 Jul 2025.
- ^ Wing FTP Server. Advisories and fixes: wftpserver.com, vicarius.io.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.939, percentile 99.8, 31 Oct 2026.
- CVE Program. “CVE-2025-47812”. 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.