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10 vulnerabilities found for wolfSSH by wolfSSL Inc.
CVE-2026-84897 (GCVE-0-2026-84897)
Vulnerability from nvd – Published: 2026-10-07 02:42 – Updated: 2026-10-07 18:37
VLAI
EPSS
VEX
Title
wolfSSH server accepts server-to-client DH group exchange messages from an unauthenticated client, causing pre-authentication primality-test CPU exhaustion and key exchange role confusion
Summary
src/internal.c in wolfSSL wolfSSH through 1.5.0 admits the server-to-client Diffie-Hellman group exchange messages SSH_MSG_KEX_DH_GEX_GROUP (31) and SSH_MSG_KEX_DH_GEX_REPLY (33) when a server receives them from an unauthenticated client. IsMessageAllowedServer() applies no direction check to the key exchange message range: when the peer is keying and no particular message is expected, which is the state a server is in for the whole window after it processes the client's KEXINIT because nothing sets handshake->expectMsgId there, the function falls out of its expectation branch without a verdict and reaches a numeric bound that admits every message id from 30 through 34. A client that negotiates diffie-hellman-group-exchange-sha256 and then sends message 31 makes the server run the client-side handler DoKexDhGexGroup(), which validates the attacker-supplied group with two 8-round Miller-Rabin primality tests, one on p and one on (p-1)/2, on a value of up to 8192 bits. The handler then returns success: the server stores the attacker's prime and generator, generates a Diffie-Hellman key pair in the attacker's group, and sends the client-role message SSH_MSG_KEX_DH_GEX_INIT (32) back to the attacker. Published RFC 3526 safe primes are the worst-case input and cost the attacker nothing to obtain. The primality validation was added in 1.5.0; versions from 1.2.0 through 1.4.22 admit the same message and enter the same client-role path without the primality cost. Message 33 is admitted as well, but on a server it is rejected before any cryptography because no public key check callback is registered, so it carries no comparable cost. Builds that define WOLFSSH_NO_DH_GEX_SHA256, which is implied by WOLFSSH_NO_DH or NO_SHA256, are unaffected.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-07 18:36 UTC
CWE
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/wolfSSL/wolfssh/pull/1221 | patch |
| https://github.com/wolfSSL/wolfssh/commit/a472f1e… | patch |
| https://www.rfc-editor.org/rfc/rfc4419.html | technical-description |
| https://www.rfc-editor.org/rfc/rfc3526.html | technical-description |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| wolfSSL Inc. | wolfSSH |
Affected:
1.2.0 , ≤ 1.5.0
(semver)
|
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CVE-2026-83742 (GCVE-0-2026-83742)
Vulnerability from nvd – Published: 2026-10-07 02:41 – Updated: 2026-10-07 11:30
VLAI
EPSS
VEX
Title
wstrncat() unsigned integer underflow leads to an off-by-one null write in wolfSSH on non-Windows platforms
Summary
Unsigned integer underflow in wstrncat() in src/port.c in wolfSSL wolfSSH from v1.4.11 through v1.5.0 on non-Windows platforms allows an authenticated remote attacker to write one out-of-bounds null byte past the end of a stack buffer by sending a crafted SFTP path. wolfSSH_RealPath() in src/ssh.c appends each path component with a remaining-size bound (outSz - curSz) rather than the full destination size, so once the accumulated path reaches half the output buffer the size_t computation n - strlen(s1) - 1 wraps to near SIZE_MAX. The strncat() call is then effectively unbounded and copies the whole component; when that component exactly fills the remainder of the buffer, its terminating null is written one byte past the end. The caller's own length check keeps the copied data inside the buffer, so the overflow is limited to that single null byte, which may corrupt an adjacent stack value and crash the process. Applications that call the public wolfSSH_RealPath() with an output buffer smaller than the input path are additionally exposed to an unbounded copy, because the word32 expression outSz - segSz in that length check also wraps.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-07 11:30 UTC
CWE
Assigner
References
4 references
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| wolfSSL Inc. | wolfSSH |
Affected:
1.4.11 , ≤ 1.5.0
(semver)
|
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CVE-2026-81535 (GCVE-0-2026-81535)
Vulnerability from nvd – Published: 2026-10-07 02:39 – Updated: 2026-10-07 18:37
VLAI
EPSS
VEX
Title
wolfSSH SSH client accepts unsolicited forwarded-tcpip channel opens without an authorization check
Summary
In wolfSSH through 1.5.0 built with --enable-fwd, DoChannelOpen() in src/internal.c gates only direct-tcpip channel opens with the forwarding policy callback. forwarded-tcpip opens are admitted without an authorization check and are not capped in number, allowing a malicious SSH peer to make an endpoint allocate unbounded per-channel buffers for forwarding channels the application never authorized. A client also does not check a forwarded-tcpip open against the forwards it registered with a tcpip-forward request, as RFC 4254 section 7.2 requires, so a malicious server can open forwarding channels for addresses and ports the client never asked it to forward.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-07 18:37 UTC
Assigner
References
3 references
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| wolfSSL Inc. | wolfSSH |
Affected:
1.4.8 , ≤ 1.5.0
(semver)
|
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CVE-2026-16516 (GCVE-0-2026-16516)
Vulnerability from nvd – Published: 2026-10-07 02:38 – Updated: 2026-10-07 11:17
VLAI
EPSS
VEX
Title
wolfSSH ECDSA host key curve not validated against negotiated algorithm
Summary
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 negotiated ssh->handshake->pubKeyId, and the RFC 5656 curve identifier string is discarded via GetSkip() rather than compared. An active network man-in-the-middle attacker can substitute a host key blob containing a different ECDSA curve, causing the client to import the key on the wrong curve. Because the attacker controls the private key for the substituted curve, signature verification passes. Exploitation requires an active MitM position and a lax public key check callback (e.g., TOFU, algorithm-name-only check, or fingerprint match against the parsed key).
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-07 11:15 UTC
CWE
- CWE-345 - Insufficient Verification of Data Authenticity
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/wolfSSL/wolfssh/issues/1012 | issue-tracking |
| https://github.com/wolfSSL/wolfssh/commit/31d1369… | patch |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| wolfSSL Inc. | wolfSSH |
Affected:
0 , ≤ 1.5.0
(semver)
|
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CVE-2024-2873 (GCVE-0-2024-2873)
Vulnerability from nvd – Published: 2024-03-25 21:58 – Updated: 2024-08-01 19:50
VLAI
EPSS
VEX
Title
User authentication bypass in wolfSSH server
Summary
A vulnerability was found in wolfSSH's server-side state machine before versions 1.4.17. A malicious client could create channels without first performing user authentication, resulting in unauthorized access.
Severity
9.1 (Critical)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-08-01 19:41 UTC
CWE
- CWE-287 - Improper Authentication
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/wolfSSL/wolfssh/pull/670 | patch |
| https://github.com/wolfSSL/wolfssh/pull/671 | patch |
| https://www.wolfssl.com/docs/security-vulnerabilities/ | vendor-advisory |
Impacted products
2 products
| Vendor | Product | Version | |
|---|---|---|---|
| wolfSSL Inc. | wolfSSH |
Affected:
0 , ≤ v1.4.16
(release bundle)
|
|
| wolfssh | wolfssh |
Affected:
0 , < 1.4.16
(custom)
cpe:2.3:a:wolfssh:wolfssh:*:*:*:*:*:*:*:* |
Date Public
2024-03-25 23:00
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CVE-2026-84897 (GCVE-0-2026-84897)
Vulnerability from cvelistv5 – Published: 2026-10-07 02:42 – Updated: 2026-10-07 18:37
VLAI
EPSS
VEX
Title
wolfSSH server accepts server-to-client DH group exchange messages from an unauthenticated client, causing pre-authentication primality-test CPU exhaustion and key exchange role confusion
Summary
src/internal.c in wolfSSL wolfSSH through 1.5.0 admits the server-to-client Diffie-Hellman group exchange messages SSH_MSG_KEX_DH_GEX_GROUP (31) and SSH_MSG_KEX_DH_GEX_REPLY (33) when a server receives them from an unauthenticated client. IsMessageAllowedServer() applies no direction check to the key exchange message range: when the peer is keying and no particular message is expected, which is the state a server is in for the whole window after it processes the client's KEXINIT because nothing sets handshake->expectMsgId there, the function falls out of its expectation branch without a verdict and reaches a numeric bound that admits every message id from 30 through 34. A client that negotiates diffie-hellman-group-exchange-sha256 and then sends message 31 makes the server run the client-side handler DoKexDhGexGroup(), which validates the attacker-supplied group with two 8-round Miller-Rabin primality tests, one on p and one on (p-1)/2, on a value of up to 8192 bits. The handler then returns success: the server stores the attacker's prime and generator, generates a Diffie-Hellman key pair in the attacker's group, and sends the client-role message SSH_MSG_KEX_DH_GEX_INIT (32) back to the attacker. Published RFC 3526 safe primes are the worst-case input and cost the attacker nothing to obtain. The primality validation was added in 1.5.0; versions from 1.2.0 through 1.4.22 admit the same message and enter the same client-role path without the primality cost. Message 33 is admitted as well, but on a server it is rejected before any cryptography because no public key check callback is registered, so it carries no comparable cost. Builds that define WOLFSSH_NO_DH_GEX_SHA256, which is implied by WOLFSSH_NO_DH or NO_SHA256, are unaffected.
Severity
SSVC
Exploitation: none
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-07 18:36 UTC
CWE
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/wolfSSL/wolfssh/pull/1221 | patch |
| https://github.com/wolfSSL/wolfssh/commit/a472f1e… | patch |
| https://www.rfc-editor.org/rfc/rfc4419.html | technical-description |
| https://www.rfc-editor.org/rfc/rfc3526.html | technical-description |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| wolfSSL Inc. | wolfSSH |
Affected:
1.2.0 , ≤ 1.5.0
(semver)
|
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CVE-2026-83742 (GCVE-0-2026-83742)
Vulnerability from cvelistv5 – Published: 2026-10-07 02:41 – Updated: 2026-10-07 11:30
VLAI
EPSS
VEX
Title
wstrncat() unsigned integer underflow leads to an off-by-one null write in wolfSSH on non-Windows platforms
Summary
Unsigned integer underflow in wstrncat() in src/port.c in wolfSSL wolfSSH from v1.4.11 through v1.5.0 on non-Windows platforms allows an authenticated remote attacker to write one out-of-bounds null byte past the end of a stack buffer by sending a crafted SFTP path. wolfSSH_RealPath() in src/ssh.c appends each path component with a remaining-size bound (outSz - curSz) rather than the full destination size, so once the accumulated path reaches half the output buffer the size_t computation n - strlen(s1) - 1 wraps to near SIZE_MAX. The strncat() call is then effectively unbounded and copies the whole component; when that component exactly fills the remainder of the buffer, its terminating null is written one byte past the end. The caller's own length check keeps the copied data inside the buffer, so the overflow is limited to that single null byte, which may corrupt an adjacent stack value and crash the process. Applications that call the public wolfSSH_RealPath() with an output buffer smaller than the input path are additionally exposed to an unbounded copy, because the word32 expression outSz - segSz in that length check also wraps.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-07 11:30 UTC
CWE
Assigner
References
4 references
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| wolfSSL Inc. | wolfSSH |
Affected:
1.4.11 , ≤ 1.5.0
(semver)
|
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CVE-2026-81535 (GCVE-0-2026-81535)
Vulnerability from cvelistv5 – Published: 2026-10-07 02:39 – Updated: 2026-10-07 18:37
VLAI
EPSS
VEX
Title
wolfSSH SSH client accepts unsolicited forwarded-tcpip channel opens without an authorization check
Summary
In wolfSSH through 1.5.0 built with --enable-fwd, DoChannelOpen() in src/internal.c gates only direct-tcpip channel opens with the forwarding policy callback. forwarded-tcpip opens are admitted without an authorization check and are not capped in number, allowing a malicious SSH peer to make an endpoint allocate unbounded per-channel buffers for forwarding channels the application never authorized. A client also does not check a forwarded-tcpip open against the forwards it registered with a tcpip-forward request, as RFC 4254 section 7.2 requires, so a malicious server can open forwarding channels for addresses and ports the client never asked it to forward.
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-07 18:37 UTC
Assigner
References
3 references
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| wolfSSL Inc. | wolfSSH |
Affected:
1.4.8 , ≤ 1.5.0
(semver)
|
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CVE-2026-16516 (GCVE-0-2026-16516)
Vulnerability from cvelistv5 – Published: 2026-10-07 02:38 – Updated: 2026-10-07 11:17
VLAI
EPSS
VEX
Title
wolfSSH ECDSA host key curve not validated against negotiated algorithm
Summary
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 negotiated ssh->handshake->pubKeyId, and the RFC 5656 curve identifier string is discarded via GetSkip() rather than compared. An active network man-in-the-middle attacker can substitute a host key blob containing a different ECDSA curve, causing the client to import the key on the wrong curve. Because the attacker controls the private key for the substituted curve, signature verification passes. Exploitation requires an active MitM position and a lax public key check callback (e.g., TOFU, algorithm-name-only check, or fingerprint match against the parsed key).
Severity
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-07 11:15 UTC
CWE
- CWE-345 - Insufficient Verification of Data Authenticity
Assigner
References
2 references
| URL | Tags |
|---|---|
| https://github.com/wolfSSL/wolfssh/issues/1012 | issue-tracking |
| https://github.com/wolfSSL/wolfssh/commit/31d1369… | patch |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| wolfSSL Inc. | wolfSSH |
Affected:
0 , ≤ 1.5.0
(semver)
|
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CVE-2024-2873 (GCVE-0-2024-2873)
Vulnerability from cvelistv5 – Published: 2024-03-25 21:58 – Updated: 2024-08-01 19:50
VLAI
EPSS
VEX
Title
User authentication bypass in wolfSSH server
Summary
A vulnerability was found in wolfSSH's server-side state machine before versions 1.4.17. A malicious client could create channels without first performing user authentication, resulting in unauthorized access.
Severity
9.1 (Critical)
SSVC
Exploitation: none
Automatable: yes
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-08-01 19:41 UTC
CWE
- CWE-287 - Improper Authentication
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/wolfSSL/wolfssh/pull/670 | patch |
| https://github.com/wolfSSL/wolfssh/pull/671 | patch |
| https://www.wolfssl.com/docs/security-vulnerabilities/ | vendor-advisory |
Impacted products
2 products
| Vendor | Product | Version | |
|---|---|---|---|
| wolfSSL Inc. | wolfSSH |
Affected:
0 , ≤ v1.4.16
(release bundle)
|
|
| wolfssh | wolfssh |
Affected:
0 , < 1.4.16
(custom)
cpe:2.3:a:wolfssh:wolfssh:*:*:*:*:*:*:*:* |
Date Public
2024-03-25 23:00
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