CVE-2024-11667
CVE-2024-11667 is a security flaw in Zyxel Multiple Firewalls, firewalls and routers for homes and small businesses. Attackers can read files on Zyxel Multiple Firewalls that should be out of reach. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 3 Dec 2024, and says ransomware gangs have used it.[1]
Zyxel Multiple Firewalls is in things households have: home and small-office routers, so the fix matters at home as much as at work. Fixed in version 5.38 of usg_flex_50w_firmware.
Description
CISA calls it a path traversal in Zyxel Multiple Firewalls. In its words: “Multiple Zyxel firewalls contain a path traversal vulnerability in the web management interface that could allow an attacker to download or upload files via a crafted URL.”[1]
The CVE record adds: “A directory traversal vulnerability in the web management interface of Zyxel ATP series firmware versions V5.00 through V5.38, USG FLEX series firmware versions V5.00 through V5.38, USG FLEX 50(W) series firmware versions V5.10 through V5.38, and USG20(W)-VPN series firmware versions V5.10 through V5.38 could allow an attacker to download or upload files via a crafted URL.”[2]
The underlying weakness is path traversal (CWE-22), 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 lists one fixed version: everything before it is affected.[2]
| Product | Fixed in |
|---|---|
| usg_flex_50w_firmware | 5.38 |
Every device with Zyxel Multiple Firewalls needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 3 Dec 2024, 6 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 24 Dec 2024 to fix it.[1] CISA says ransomware gangs have used it.
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 13% 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
Zyxel has published a fix or advice.[3] CISA’s required action: “Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.”[1]
- Update Zyxel Multiple Firewalls now.Open the router’s app, or its admin page in a browser, and look for a firmware update. Then turn on automatic updates, so the next fix arrives on its own.
- Check you’re on 5.38 or later.Fixed in version 5.38 of usg_flex_50w_firmware. Anything older is what attackers are going after.
- If the maker has stopped updating it, replace it.Routers stop getting fixes after a few years, and attackers keep a list of the ones that did. If there’s no newer firmware, it won’t be fixed.
Timeline
| Date | Event |
|---|---|
| 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, noting that ransomware gangs have used it.[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 Zyxel Multiple Firewalls flaws
- CVE-2023-33010: buffer overflow ·
- CVE-2023-33009: buffer overflow ·
- CVE-2023-28771: OS command injection ·
- CVE-2022-30525: OS command injection ·
Other Zyxel flaws
- CVE-2026-7273, Zyxel GS1900 Series Switches: stack-based buffer overflow ·
- CVE-2024-40891, Zyxel DSL CPE Devices: DSL CPE OS command injection ·
- CVE-2024-40890, Zyxel DSL CPE Devices: DSL CPE OS command injection ·
- CVE-2017-6884, Zyxel EMG2926 Routers: command injection ·
- CVE-2017-18368, Zyxel P660HN-T1A Routers: command injection ·
Other path traversal flaws
- CVE-2025-61624, Fortinet products: path traversal ·
- CVE-2021-3199, ONLYOFFICE Docs: server path traversal ·
- CVE-2026-104286, Fortinet FortiMail: path traversal ·
- CVE-2026-93616, Check Point products: path traversal ·
- CVE-2026-66384, JFrog Artifactory: improper limitation of a pathname to a restricted directory ·
Added the same day
- CVE-2024-11680, ProjectSend: improper authentication ·
- CVE-2023-45727, North Grid Proself: improper restriction of XML external entity (XXE) reference ·
Every Zyxel flaw on CISA’s list · Everything added in December 2024
References
- ^ Cybersecurity and Infrastructure Security Agency. “Zyxel Multiple Firewalls Path Traversal Vulnerability”. Known Exploited Vulnerabilities Catalog, added 3 Dec 2024.
- ^ National Institute of Standards and Technology. “CVE-2024-11667 Detail”. National Vulnerability Database, published 27 Nov 2024.
- ^ Zyxel. Advisories and fixes: zyxel.com, zyxel.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.029, percentile 87.1, 31 Oct 2026.
- CVE Program. “CVE-2024-11667”. 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.