CVE-2023-39780
CVE-2023-39780 is a security flaw in ASUS RT-AX55 Routers, routers for homes and small offices. Someone who already has a way in can use ASUS RT-AX55 Routers to run their own code. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 2 Jun 2025.[1]
ASUS RT-AX55 Routers is in things households have: home and small-office routers, so the fix matters at home as much as at work. ASUS has published a fix or advice.
Description
CISA calls it an OS command injection in ASUS RT-AX55 Routers. In its words: “ASUS RT-AX55 devices contain an OS command injection vulnerability that could allow a remote, authenticated attacker to execute arbitrary commands. As represented by CVE-2023-41346.”[1]
The CVE record adds: “On ASUS RT-AX55 3.0.0.4.386.51598 devices, authenticated attackers can perform OS command injection via the /start_apply.htm qos_bw_rulelist parameter. NOTE: for the similar "token-generated module" issue, see CVE-2023-41345; for the similar "token-refresh module" issue, see CVE-2023-41346; for the similar "check token module" issue, see CVE-2023-41347; and for the similar "code-authentication module" issue, see CVE-2023-41348.”[2]
The underlying weakness is OS command injection (CWE-78), in MITRE’s list of common software weaknesses.
It scores 8.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; ASUS’s advisory has them[3]. CISA names the product as ASUS RT-AX55 Routers.
Every device with ASUS RT-AX55 Routers needs the update.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 2 Jun 2025, 630 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 23 Jun 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 40%. That’s in the top 2% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
ASUS 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]
- Update ASUS RT-AX55 Routers 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.
- 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 8.8.[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 40%.[4] |
See also
Other ASUS flaws
- CVE-2025-59374, ASUS Live Update: embedded malicious code ·
- CVE-2021-32030, ASUS Routers: improper authentication ·
Other OS command injection flaws
- CVE-2026-110447, Collabora Online – Built-in CODE Server: online – built-in CODE server OS command injection ·
- CVE-2026-106931, EG Secure Solutions SiteGuard Server Edition: OS command injection ·
- CVE-2026-83549, SonicWall SMA1000 Appliances: OS command injection ·
- CVE-2026-49869, Kestra OSS: OSS OS command injection ·
- CVE-2026-73570, Synacor Zimbra Collaboration Suite (ZCS): OS command injection ·
Added the same day
- CVE-2025-3935, ConnectWise ScreenConnect: improper authentication ·
- CVE-2025-35939, Craft CMS: external control of assumed-immutable web parameter ·
- CVE-2024-56145, Craft CMS: code injection ·
- CVE-2021-32030, ASUS Routers: improper authentication ·
Every ASUS flaw on CISA’s list · Everything added in June 2025
References
- ^ Cybersecurity and Infrastructure Security Agency. “ASUS RT-AX55 Routers OS Command Injection Vulnerability”. Known Exploited Vulnerabilities Catalog, added 2 Jun 2025.
- ^ National Institute of Standards and Technology. “CVE-2023-39780 Detail”. National Vulnerability Database, published 11 Sep 2023.
- ^ ASUS. Advisories and fixes: asus.com, asus.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.395, percentile 98.6, 31 Oct 2026.
- CVE Program. “CVE-2023-39780”. 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.