CVE-2026-67279
CVE-2026-67279 is a security flaw in MikroTik RouterOS, the operating system on MikroTik’s routers. Attackers are using a flaw in MikroTik RouterOS. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 25 Sep 2026.[1]
MikroTik RouterOS 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 7.24.2, 7.23.4 and 6.49.21 of RouterOS.
Description
CISA calls it an improper enforcement of behavioral workflow in MikroTik RouterOS. In its words: “Mikrotik RouterOS contains an improper enforcement of behavioral workflow vulnerability that could allow an unauthenticated client to open a session channel and send an exec request. This vulnerability can be chained to achieve unauthenticated exploitation of CVE-2026-86060.”[1]
The CVE record adds: “RouterOS SSH enters the connection protocol after a client-requested rekey even though user authentication was never attempted, allowing an unauthenticated client to open a session channel and send an exec request. On affected builds the server dispatches the command, enabling unauthenticated creation, overwrite, and reconstruction of files in the RouterOS managed file namespace, including support files containing configuration and diagnostic data.This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)”[2]
The underlying weakness is CWE-841, in MITRE’s list of common software weaknesses.
It scores 6.5 out of 10 on the Common Vulnerability Scoring System, which rates it medium, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record lists these fixed versions: in each line, everything before the version shown is affected.[2]
| Product | Fixed in |
|---|---|
| RouterOS | 7.24.2 |
| RouterOS | 7.23.4 |
| RouterOS | 6.49.21 |
Most families won’t have MikroTik RouterOS; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 25 Sep 2026, 20 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 28 Sep 2026 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 2%. That’s in the top 17% 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
MikroTik has published a fix or advice.[3] CISA’s required action: “Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes).”[1]
- Check whether you use it.MikroTik RouterOS 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 7.24.2, 7.23.4 and 6.49.21 of RouterOS), or not in use. CISA gave US government agencies until 28 Sep 2026 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 6.5.[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 2%.[4] |
See also
Other MikroTik RouterOS flaws
- CVE-2026-86060: improper neutralization of argument delimiters in a command ·
- CVE-2026-67277: missing authentication for critical function ·
- CVE-2018-7445: stack-based buffer overflow ·
- CVE-2018-14847: router OS directory traversal ·
Added the same day
- CVE-2026-87902, WordPress Core: remote file inclusion ·
- CVE-2026-65660, Microsoft SharePoint: code injection ·
Every MikroTik flaw on CISA’s list · Everything added in September 2026
References
- ^ Cybersecurity and Infrastructure Security Agency. “Mikrotik RouterOS Improper Enforcement of Behavioral Workflow Vulnerability”. Known Exploited Vulnerabilities Catalog, added 25 Sep 2026.
- ^ National Institute of Standards and Technology. “CVE-2026-67279 Detail”. National Vulnerability Database, published 5 Sep 2026.
- ^ MikroTik. Advisories and fixes: mikrotik.com, cert.pl, forum.mikrotik.com, forum.mikrotik.com, forum.mikrotik.com, and 1 more on NVD’s record.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.023, percentile 83.1, 31 Oct 2026.
- CVE Program. “CVE-2026-67279”. 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.