Kernel memory disclosure and denial of service in MikroTik RouterOS btest service
Affects RouterOS 6.x before 6.49.21, 7.x before 7.23.4, and 7.24 before 7.24.2 where the btest bandwidth-test service is reachable. Fixed in 7.24.2, 7.23.4 and 6.49.21.
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Actively exploited
- Fix
- Fixed in 7.24.2, 7.23.4, 6.49.21
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
MikroTik RouterOS, specifically its btest bandwidth test service, is affected. An unauthenticated remote client can exploit the service to leak uninitialized kernel memory and crash the router's kernel, causing a denial of service.
Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.
Read the original description
RouterOS accepts a "related" btest connection before the corresponding primary session has completed authentication. An unauthenticated client can use this state to start an IPv4 UDP test. With "random-data=false", the sender transmits an uninitialized tail from a kernel packet buffer. A separate unchecked, inverted packet-size interval causes unsigned integer underflow, anomalously large fragmented output, and can restart the RouterOS kernel. This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)
Timeline
- CVE published
- Added to CISA KEV
CISA has evidence of exploitation in the wild
- Record last updated
- CISA remediation deadline
Due date for US federal agencies to patch
Affected versions
- Mikrotik RouterOS
From 7.24 · fixed in 7.24.2; From 7.0.0 · fixed in 7.23.4; From 6.0.0 · fixed in 6.49.21
References 7
cert.pl
mikrotik.com
Questions about CVE-2026-67277
What does this mean?
A crafted request to the btest bandwidth-test service can crash the router or reveal small amounts of kernel memory contents.Source: mikrotik.com
Am I affected, and how do I check?
RouterOS 6.0.0 before 6.49.21, 7.0.0 before 7.23.4, and 7.24 before 7.24.2 are in the affected ranges, but only where the btest bandwidth-test service is reachable and handles a crafted request. Check the installed RouterOS version and whether the bandwidth-test service is reachable.Source: mikrotik.com
What should I do about it?
Upgrade to the fixed release for the installed branch: 6.49.21, 7.23.4, or 7.24.2.Source: mikrotik.com
Is it being exploited?
Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-09-10, which means it has evidence of attacks. No public exploit code is tracked.Source: cisa.gov, cve.now feed data