CVE-2026-67276

Published Sep 5, 2026

Last updated a day ago

CVSS critical 9.2
SSH
RouterOS

Overview

AI description

Automated description summarized from trusted sources.

CVE-2026-67276 is an SSH authentication bypass vulnerability affecting MikroTik RouterOS. The flaw stems from an incomplete verification process of RSA public keys during SSH authentication. Specifically, RouterOS checks the key type and modulus but fails to compare the entire RSA public key, omitting the exponent. This oversight allows an attacker, who possesses knowledge of a user's public modulus, to forge a different key and successfully log in via SSH without needing the corresponding private key. This vulnerability has been actively exploited as part of a larger attack chain dubbed "MikroTrick" and has been addressed in RouterOS versions 6.49.21 (Long-term), 7.23.4 (Long-term), and 7.24.2 (Stable).

Description
RouterOS does not compare the complete RSA public key when matching an SSH authentication request to an authorized user key, checking the key type and modulus but omitting the exponent. Because signature verification uses the client-supplied key, an attacker knowing an authorized RSA modulus can supply a key with exponent one, forge a valid signature, and open an SSH command channel as the target user without the private key.This issue was fixed in versions: 6.49.21 (Long-term), 7.23.4 (Long-term) and 7.24.2 (Stable)
Source
cvd@cert.pl
NVD status
Received

Risk scores

CVSS 4.0

Type
Secondary
Base score
9.2
Impact score
-
Exploitability score
-
Vector string
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Severity
CRITICAL

Weaknesses

cvd@cert.pl
CWE-347

Social media

Hype score is a measure of social media activity compared against trending CVEs from the past 12 months. Max score 100.

Hype score

23

  1. 🔴 MikroTrick — MikroTik routers under active attack Attackers are exploiting CVE-2026-67276 + CVE-2026-86060 against Internet-exposed RouterOS devices. The chain https://t.co/RSJXdyWeNL #CVE #CVE202667276 #CVE202686060 #MikroTik #RouterOS #MikroTrick #CyberSecurity #Info

    @stem__shop

    6 Sept 2026

    15 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

  2. MikroTrick zero-day chain gives unauthenticated attackers admin control of MikroTik RouterOS via internet-exposed SSH (CVE-2026-67276 CVSS 9.2 + CVE-2026-86060). Patch and block WAN SSH now. #MikroTik #ZeroDay #CyberSecurity https://t.co/adE7FghxsF

    @CyberWorldOps

    6 Sept 2026

    24 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

  3. MikroTrick is live. https://t.co/aUq4IvI1fF just dropped 6 RouterOS bugs, already exploited in the wild. CVE-2026-67276 is a critical SSH pubkey auth bypass (CVSS 9.2). Patch now: 7.25beta3 / 7.24.2 / 7.23.4 / 6.49.21 PoC: https://t.co/SaxzbFOdAC Advisory:

    @LandscapeThreat

    6 Sept 2026

    61 Impressions

    0 Retweets

    3 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

  4. It took us 3 hours to rewrite the full pre-auth RCE MikroTrick chain (CVE-2026-67279, CVE-2026-86060, CVE-2026-67276) from the public advisory. https://t.co/4tmLd8aAFq

    @TolmoHQ

    6 Sept 2026

    2212 Impressions

    5 Retweets

    13 Likes

    6 Bookmarks

    2 Replies

    1 Quote

  5. MikroTik RouterOS zero-day chain "MikroTrick" under active exploitation since Sept 2, combining SSH auth bypass (CVE-2026-67276, CVSS 9.2) and privilege escalation to deliver unauthenticated full admin access. Key findings: - CVE-2026-67276 abuses a flaw in RSA public key https

    @DFIR_Radar

    6 Sept 2026

    185 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    1 Reply

    0 Quotes

  6. MikroTrick lab PoC — CVE-2026-67276 (RouterOS SSH public-key auth bypass) https://t.co/qFygGgipfY

    @Dinosn

    6 Sept 2026

    17418 Impressions

    64 Retweets

    276 Likes

    189 Bookmarks

    4 Replies

    3 Quotes

  7. CVE-2026-67276 RouterOS SSH public-key authentication bypass lab PoC https://t.co/qFygGgipfY

    @Dinosn

    6 Sept 2026

    823 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

  8. MikroTik “MikroTrick”CERT Polska found six RouterOS bugs. Two chained together give full admin with no password if SSH is on the public internet. They named the chain https://t.co/wi9xRV6P4y it works:CVE-2026-67276: SSH does not check the full RSA key. It checks type + modulu

    @ichbinlucasv

    6 Sept 2026

    5 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

  9. 🚨 #CVE-2026-67276: Critical SSH Authentication Bypass in MikroTik RouterOS Enables Unauthenticated Device Takeover + Video -Prediction: 📈 1 Positive | 📉 2 Negative https://t.co/wFgeVHS5mn Educational Purposes!

    @UndercodeUpdate

    6 Sept 2026

    70 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

Related CVEs

  1. libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftp_open() function in src/sftp.c that allows a malicious SSH server to corrupt the heap of any authenticated client opening an SFTP session. When a server responds to SSH_FXP_OPEN with SSH_FXP_STATUS containing FX_OK, the response data buffer is freed, and if a subsequent sftp_packet_require() call returns a specific error such as LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, the same pointer is freed a second time, enabling tcache dup conditions on glibc systems that allow overlapping allocations and function pointer overwrites.•CVE-2026-66032
  2. libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2_cipher_crypt() function in src/openssl.c that allows a malicious SSH server to crash any connecting client by negotiating AES-GCM ciphers during handshake. Attackers can exploit the underflow in the expression computing blocksize minus aadlen minus authentication tag length to trigger an out-of-bounds read and a memcpy call with a near-SIZE_MAX length argument, causing immediate process crash before any authentication occurs.•CVE-2026-66033
  3. libssh2 through 1.11.1, fixed in commit a13bb6c, contains a missing bounds check vulnerability that allows a malicious SSH server to trigger an arbitrary-length heap out-of-bounds read and a free of an uninitialized pointer via the publickey subsystem. In libssh2_publickey_list_fetch(), the version 1 response parser reads a server-controlled comment_len value and advances the parse pointer without verifying sufficient bytes remain in the buffer, causing the out-of-bounds read to leak heap pointers from adjacent allocations defeating ASLR, followed by heap allocator state corruption when the error cleanup path frees an uninitialized pointer from a non-zeroed realloc() region.•CVE-2026-66034
  4. libssh2 through 1.11.1, fixed in commit 42e33d8, contains a pre-authentication heap buffer overflow vulnerability that allows a malicious SSH server to corrupt heap metadata in any connecting client by sending a packet with a packet_length smaller than the cipher's block size during Encrypt-then-MAC cipher negotiation. In the fullpacket() function in src/transport.c, the ETM path allocates a buffer of packet_length bytes but copies blocksize minus one bytes via memcpy, causing an overflow that on 32-bit glibc writes attacker-controlled bytes into an adjacent chunk's SIZE field, enabling tcache bin confusion, overlapping live objects, and function pointer overwrite during the session handshake before authentication.•CVE-2026-66035
  5. A Missing Authentication vulnerability was discovered in the SSH keys synchronization endpoint. An unauthenticated attacker can send a request to the SSH keys synchronization endpoint and obtain the list of users that have uploaded their public SSH keys, their groups, and the uploaded public SSH keys.•CVE-2026-31983

References

Sources include official advisories and independent security research.