Date: October 6, 2026 Severity: High Affected Users: Operators of wolfSSHd on Windows, wolfSSH versions 1.4.15 through 1.5.0. Non-Windows builds are not affected. Fixed In: wolfSSH v1.6.0 (PR 1163) Summary On Windows, wolfSSHd used a single authentication context, and the logon token stored in it, for every concurrent connection. A user with a valid account […]

Date: October 6, 2026 Severity: High Affected Users: Operators of wolfSSHd on Windows, wolfSSH versions 1.4.15 through 1.5.0. Non-Windows builds are not affected. Fixed In: wolfSSH v1.6.0 (PR 1163) Summary On Windows, wolfSSHd used a single authentication context, and the logon token stored in it, for every concurrent connection. A user with a valid account […]

Date: October 6, 2026 Severity: Medium Affected Users: Servers and applications using wolfSSH versions 1.4.11 through 1.5.0 on non-Windows platforms. Applications that call wolfSSH_RealPath() directly are additionally exposed (see below). Fixed In: wolfSSH v1.6.0 (PR 1084) Summary wolfSSH_RealPath() could be driven to write one byte past the end of a stack buffer. A crafted SFTP […]

Date: October 6, 2026 Severity: Medium Affected Users: Servers and applications using wolfSSH versions 1.4.11 through 1.5.0 on non-Windows platforms. Applications that call wolfSSH_RealPath() directly are additionally exposed (see below). Fixed In: wolfSSH v1.6.0 (PR 1084) Summary wolfSSH_RealPath() could be driven to write one byte past the end of a stack buffer. A crafted SFTP […]

Date: October 6, 2026 Severity: Medium Affected Users: Operators of wolfSSH servers, wolfSSH versions 1.2.0 through 1.5.0. Builds with WOLFSSH_NO_DH_GEX_SHA256 defined are not affected. Fixed In: wolfSSH v1.6.0 (PR 1221) Summary A wolfSSH server accepted two key exchange messages that only a server should ever send. An unauthenticated client could use one of them to […]

Date: October 6, 2026 Severity: Medium Affected Users: Operators of wolfSSH servers, wolfSSH versions 1.2.0 through 1.5.0. Builds with WOLFSSH_NO_DH_GEX_SHA256 defined are not affected. Fixed In: wolfSSH v1.6.0 (PR 1221) Summary A wolfSSH server accepted two key exchange messages that only a server should ever send. An unauthenticated client could use one of them to […]

Date: October 6, 2026 Severity: Medium Affected Users: Applications built with –enable-fwd (port forwarding), wolfSSH versions 1.4.8 through 1.5.0. Fixed In: wolfSSH v1.6.0 (PR 1059, 1148, 1220) Summary With forwarding enabled, wolfSSH admitted forwarded-tcpip channel opens without consulting the application’s forwarding policy callback, and a client accepted them for forwards it had never requested. A […]

Date: October 6, 2026 Severity: Medium Affected Users: Applications built with –enable-fwd (port forwarding), wolfSSH versions 1.4.8 through 1.5.0. Fixed In: wolfSSH v1.6.0 (PR 1059, 1148, 1220) Summary With forwarding enabled, wolfSSH admitted forwarded-tcpip channel opens without consulting the application’s forwarding policy callback, and a client accepted them for forwards it had never requested. A […]

Date: October 6, 2026 Severity: Critical Affected Users: Applications using the wolfSSH client with wolfSSH releases through v1.5.0 that rely on ECDSA host keys. Fixed In: wolfSSH v1.6.0 (PR 1022, issue #1012) Summary A man-in-the-middle could substitute a server’s ECDSA host key with a key on a different curve and still pass signature verification, using […]

Date: October 6, 2026 Severity: Critical Affected Users: Applications using the wolfSSH client with wolfSSH releases through v1.5.0 that rely on ECDSA host keys. Fixed In: wolfSSH v1.6.0 (PR 1022, issue #1012) Summary A man-in-the-middle could substitute a server’s ECDSA host key with a key on a different curve and still pass signature verification, using […]

wolfSSH does not validate that the ECDSA curve identifier in a KEXDH_REPLY host key blob matches the algorithm negotiated during key exchange. In ParseECCPubKey() (src/internal.c), the blob's algorithm string is used to derive the curve via NameToId/wcPrimeForId without checking against the negotiat

wolfSSH v1.6.0 is now available. This release has five vulnerability fixes, strict key exchange enabled by default, ML-DSA host keys and user authentication, and the largest hardening pass wolfSSH has had. Several defaults have changed, so please read the Behavior Changes section before upgrading. See the ChangeLog.md for the full list. Vulnerabilities This release addresses […]

wolfSSH v1.6.0 is now available. This release has five vulnerability fixes, strict key exchange enabled by default, ML-DSA host keys and user authentication, and the largest hardening pass wolfSSH has had. Several defaults have changed, so please read the Behavior Changes section before upgrading. See the ChangeLog.md for the full list. Vulnerabilities This release addresses […]

wolfSSL has released wolfSSH version 1.6.0, which addresses five security vulnerabilities, including a critical flaw that could allow a man-in-the-middle attacker to bypass SSH host-key authentication under certain deployment conditions.

wolfSSLはwolfSSHのバージョン1.6.0を公開し、5件のセキュリティ脆弱性を修正しました。このうち1件は重大な欠陥で、特定の運用条件下では、中間者攻撃者がSSHホスト鍵認証を回避できる恐れがあります。Cybersecurityconsulting 2026年10月6日付のこのリリースでは、wolfSSH

wolfSSL has released wolfSSH 1.6.0 to fix five security flaws, including a critical host key verification bypass that could let an attacker impersonate an SSH server. Published on October 6, 2026, the update addresses Windows privilege escalation, unauthenticated key exchange abuse, unauthorized forwarding channels, and an SFTP memory corruption bug. The release rates one flaw critical, one high, and three medium. The most serious issue, CVE-2026-16516, affects wolfSSH through version 1.5.0. During SSH key exchange , the client failed to check whether the ECDSA curve inside the server’s host key matched the algorithm agreed upon for the connection. An attacker positioned between the client and server could replace that key with one using a different curve. Because the attacker owns the replacement key’s private key, signature verification could still succeed. However, exploitation also requires a weak public-key-checking callback in the application. This condition matters: the flaw does not mean every affected client automatically accepts an attacker’s key. wolfSSL credits researcher zhangph, known on GitHub as afldl, with reporting the issue. The high-severity issue, CVE-2026-83540, affects wolfSSHd on Windows from versions 1.4.15 through 1.5.0. Concurrent connections shared an authentication context containing a Windows logon token . Both password and public key authentication wrote to this shared token, creating a risk that a user with a valid account could receive another user’s login identity, including one with higher privileges. Non-Windows builds are unaffected. CVE-2026-84897 concerns incorrect handling of Diffie-Hellman group exchange messages. A vulnerable server accepted messages intended only for a server, allowing an unauthenticated client to trigger client-side processing. After selecting diffie-hellman-group-exchange-sha256, an attacker could submit a chosen group and force costly checks of whether its numbers are prime. wolfSSH 1.6.0 Fixes 5 Security Flaws The release notes describe roughly half a second of CPU work per 1 KB packet containing a 4096-bit prime. The message-handling flaw affects versions 1.2.0 through 1.5.0, while the expensive prime checks apply from 1.5.0. Builds using WOLFSSH_NO_DH_GEX_SHA256 are unaffected. CVE-2026-81535 affects versions 1.4.8 through 1.5.0 built with –enable-fwd. The software accepted forwarded-tcpip channel requests without checking the application’s forwarding policy. Clients also accepted channels for remote forwards they had never requested. A peer could therefore cause an endpoint to allocate buffers for forwarding channels that the application had not approved. The fifth flaw, CVE-2026-83742, affects non-Windows builds from versions 1.4.11 through 1.5.0. Incorrect length calculations in wolfSSH_RealPath() could let a crafted SFTP path write a terminating NUL byte just beyond a stack buffer. An authenticated attacker could corrupt nearby data and crash the process. Applications supplying an output buffer smaller than the input face additional exposure to an unbounded copy. Administrators and developers should upgrade affected deployments to wolfSSH 1.6.0 and review the official release notes before rollout. The update enables strict key exchange by default, adding protection against the Terrapin attack previously covered by Cyber Security News. It also requires RSA user authentication keys of at least 2048 bits and, by default, limits failed authentication attempts to six. Stops threats before impact with 21 min faster MTTR. Integrate ANYRUN’s Sandbox in your SOC The post wolfSSH 1.6.0 Fixes 5 Security Flaws Including Critical MITM Host Key Verification Bypass appeared first on Cyber Security News .

TL;DR wolfSSL has released wolfSSH 1.6.0 to fix five security flaws in its lightweight SSH library. The most serious of these wolfSSH vulnerabilities, CVE-2026-16516, scores 9.0 on CVSS 4.0 and can let a man-in-the-middle attacker pass off a forged server key. All five affect wolfSSH 1.5.0 and earlier. Why It Matters wolfSSH is built for embedded devices, IoT products and other constrained systems.

wolfSSLはwolfSSH 1.6.0をリリースし、サーバ認証、Windowsでの権限昇格、鍵交換、ポートフォワーディング、SFTPのメモリ処理にまたがる5件のセキュリティ脆弱性を修正しました。 2026年10月6日に公開されたこのアップデートでは、重大度が「クリティカル」の脆弱性が1件、「高」が1件、「中」が3

wolfSSH can be tricked into using a host key that uses a different elliptic curve than the one agreed during the connection.

Five vulnerabilities were disclosed on October 7 in wolfSSH, wolfSSL's embedded SSH library. One is rated critical, and one affects only the Windows build of the wolfSSHd server. SecNews told…