wolfSSL vulnerabilities

CVE-2026-4395 Critical · 9.8 CWE-122 Mar 19, 2026

Heap-based buffer overflow in wc_ecc_import_x963_ex KCAPI path

Heap-based buffer overflow in the KCAPI ECC code path of wc_ecc_import_x963_ex() in wolfSSL wolfcrypt allows a remote attacker to write attacker-controlled data past the bounds of the pubkey_raw buffer via a crafted oversized EC public key point. The WOLFSSL_KCAPI_ECC code path copies the input to key->pubkey_raw (132 bytes) using XMEMCPY without a bounds check, unlike the ATECC code path which includes a length validation. This can be triggered during TLS key exchange when a malicious peer sends a crafted ECPoint in ServerKeyExchange.

CVE-2026-3849 Critical · 9.8 CWE-787 Mar 19, 2026

Buffer Overflow in HPKE via Oversized ECH Config

Stack Buffer Overflow in wc_HpkeLabeledExtract via Oversized ECH Config. A vulnerability existed in wolfSSL 5.8.4 ECH (Encrypted Client Hello) support, where a maliciously crafted ECH config could cause a stack buffer overflow on the client side, leading to potential remote execution and client program crash. This could be exploited by a malicious TLS server supporting ECH. Note that ECH is off by default, and is only enabled with enable-ech.

CVE-2026-3549 Critical · 9.8 CWE-122 Mar 19, 2026

ECH parsing heap buffer overflow

Heap Overflow in TLS 1.3 ECH parsing. An integer underflow existed in ECH extension parsing logic when calculating a buffer length, which resulted in writing beyond the bounds of an allocated buffer. Note that in wolfSSL, ECH is off by default, and the ECH standard is still evolving.

CVE-2026-3547 High · 7.5 CWE-125 Mar 19, 2026

wolfSSL: out-of-bounds read (DoS) in ALPN parsing due to incomplete validation

Out-of-bounds read in ALPN parsing due to incomplete validation. wolfSSL 5.8.4 and earlier contained an out-of-bounds read in ALPN handling when built with ALPN enabled (HAVE_ALPN / --enable-alpn). A crafted ALPN protocol list could trigger an out-of-bounds read, leading to a potential process crash (denial of service). Note that ALPN is disabled by default, but is enabled for these 3rd party compatibility features: enable-apachehttpd, enable-bind, enable-curl, enable-haproxy, enable-hitch, enable-lighty, enable-jni, enable-nginx, enable-quic.

CVE-2026-3230 Low · 2.7 CWE-20 Mar 19, 2026

Improper key_share validation in TLS 1.3 HelloRetryRequest

Missing required cryptographic step in the TLS 1.3 client HelloRetryRequest handshake logic in wolfSSL could lead to a compromise in the confidentiality of TLS-protected communications via a crafted HelloRetryRequest followed by a ServerHello message that omits the required key_share extension, resulting in derivation of predictable traffic secrets from (EC)DHE shared secret. This issue does not affect the client's authentication of the server during TLS handshakes.

CVE-2026-3229 Medium · 5.5 CWE-122 Mar 19, 2026

Integer Overflow in Certificate Chain Allocation

An integer overflow vulnerability existed in the static function wolfssl_add_to_chain, that caused heap corruption when certificate data was written out of bounds of an insufficiently sized certificate buffer. wolfssl_add_to_chain is called by these API: wolfSSL_CTX_add_extra_chain_cert, wolfSSL_CTX_add1_chain_cert, wolfSSL_add0_chain_cert. These API are enabled for 3rd party compatibility features: enable-opensslall, enable-opensslextra, enable-lighty, enable-stunnel, enable-nginx, enable-haproxy. This issue is not remotely exploitable, and would require that the application context loading certificates is compromised.

CVE-2026-3580 Medium · 4.7 CWE-203 Mar 19, 2026

Compiler-induced timing leak in sp_256_get_entry_256_9 on RISC-V

In wolfSSL 5.8.4, constant-time masking logic in sp_256_get_entry_256_9 is optimized into conditional branches (bnez) by GCC when targeting RISC-V RV32I with -O3. This transformation breaks the side-channel resistance of ECC scalar multiplication, potentially allowing a local attacker to recover secret keys via timing analysis.

CVE-2026-3579 Medium · 5.9 CWE-203 Mar 19, 2026

Non-constant time multiplication subroutine __muldi3 on RISC-V RV32I

wolfSSL 5.8.4 on RISC-V RV32I architectures lacks a constant-time software implementation for 64-bit multiplication. The compiler-inserted __muldi3 subroutine executes in variable time based on operand values. This affects multiple SP math functions (sp_256_mul_9, sp_256_sqr_9, etc.), leading to a timing side-channel that may expose sensitive cryptographic data.

CVE-2026-3503 Medium · 5.2 CWE-335 Mar 19, 2026

Fault injection attack with ML-DSA and ML-KEM on ARM

Protection mechanism failure in wolfCrypt post-quantum implementations (ML-KEM and ML-DSA) in wolfSSL on ARM Cortex-M microcontrollers allows a physical attacker to compromise key material and/or cryptographic outcomes via induced transient faults that corrupt or redirect seed/pointer values during Keccak-based expansion. This issue affects wolfSSL (wolfCrypt): commit hash d86575c766e6e67ef93545fa69c04d6eb49400c6.

CVE-2026-3548 Critical · 9.8 CWE-787 Mar 19, 2026

Buffer overflow in CRL number parsing in wolfSSL

Two buffer overflow vulnerabilities existed in the wolfSSL CRL parser when parsing CRL numbers: a heap-based buffer overflow could occur when improperly storing the CRL number as a hexadecimal string, and a stack-based overflow for sufficiently sized CRL numbers. With appropriately crafted CRLs, either of these out of bound writes could be triggered. Note this only affects builds that specifically enable CRL support, and the user would need to load a CRL from an untrusted source.

CVE-2026-2646 High · 8.1 CWE-787 Mar 19, 2026

Heap buffer overflow in session parsing with wolfSSL_d2i_SSL_SESSION() function

A heap-buffer-overflow vulnerability exists in wolfSSL's wolfSSL_d2i_SSL_SESSION() function. When deserializing session data with SESSION_CERTS enabled, certificate and session id lengths are read from an untrusted input without bounds validation, allowing an attacker to overflow fixed-size buffers and corrupt heap memory. A maliciously crafted session would need to be loaded from an external source to trigger this vulnerability. Internal sessions were not vulnerable.

CVE-2026-2645 High · 7.5 CWE-358 Mar 19, 2026

Acceptance of CertificateVerify Message before ClientKeyExchange in TLS 1.2

In wolfSSL 5.8.2 and earlier, a logic flaw existed in the TLS 1.2 server state machine implementation. The server could incorrectly accept the CertificateVerify message before the ClientKeyExchange message had been received. This issue affects wolfSSL before 5.8.4 (wolfSSL 5.8.2 and earlier is vulnerable, 5.8.4 is not vulnerable). In 5.8.4 wolfSSL would detect the issue later in the handshake. 5.9.0 was further hardened to catch the issue earlier in the handshake.

CVE-2026-1005 Medium · 5.3 CWE-191 Mar 19, 2026

Integer underflow leads to out-of-bounds access in sniffer AES-GCM/CCM/ARIA-GCM decrypt path

Integer underflow in wolfSSL packet sniffer <= 5.8.4 allows an attacker to cause a buffer overflow in the AEAD decryption path by injecting a TLS record shorter than the explicit IV plus authentication tag into traffic inspected by ssl_DecodePacket. The underflow wraps a 16-bit length to a large value that is passed to AEAD decryption routines, causing heap buffer overflow and a crash. An unauthenticated attacker can trigger this remotely via malformed TLS Application Data records.

CVE-2026-0819 High · 7.1 CWE-787 Mar 19, 2026

Stack buffer overflow in PKCS7 SignedData encoding with custom signed attributes

A stack buffer overflow vulnerability exists in wolfSSL's PKCS7 SignedData encoding functionality. In wc_PKCS7_BuildSignedAttributes(), when adding custom signed attributes, the code passes an incorrect capacity value (esd->signedAttribsCount) to EncodeAttributes() instead of the remaining available space in the fixed-size signedAttribs[7] array. When an application sets pkcs7->signedAttribsSz to a value greater than MAX_SIGNED_ATTRIBS_SZ (default 7) minus the number of default attributes already added, EncodeAttributes() writes beyond the array bounds, causing stack memory corruption. In WOLFSSL_SMALL_STACK builds, this becomes heap corruption. Exploitation requires an application that allows untrusted input to control the signedAttribs array size when calling wc_PKCS7_EncodeSignedData() or related signing functions.

CVE-2025-15346 Critical · 9.3 CWE-287 Jan 7, 2026

wolfSSL Python library `CERT_REQUIRED` mode fails to enforce client certificate requirement

A vulnerability in the handling of verify_mode = CERT_REQUIRED in the wolfssl Python package (wolfssl-py) causes client certificate requirements to not be fully enforced. Because the WOLFSSL_VERIFY_FAIL_IF_NO_PEER_CERT flag was not included, the behavior effectively matched CERT_OPTIONAL: a peer certificate was verified if presented, but connections were incorrectly authenticated when no client certificate was provided. This results in improper authentication, allowing attackers to bypass mutual TLS (mTLS) client authentication by omitting a client certificate during the TLS handshake. The issue affects versions up to and including 5.8.2.

CVE-2025-14942 Critical · 9.8 CWE-287 Jan 6, 2026

Authentication Bypass

wolfSSH’s key exchange state machine can be manipulated to leak the client’s password in the clear, trick the client to send a bogus signature, or trick the client into skipping user authentication. This affects client applications with wolfSSH version 1.4.21 and earlier. Users of wolfSSH must update or apply the fix patch and it’s recommended to update credentials used. This fix is also recommended for wolfSSH server applications. While there aren’t any specific attacks on server applications, the same defect is present. Thanks to Aina Toky Rasoamanana of Valeo and Olivier Levillain of Telecom SudParis for the report.

CVE-2025-15382 High · 8.1 CWE-125 Jan 6, 2026

Client SCP Request Triggers Buffer Overread by 1 Byte

A heap buffer over-read vulnerability exists in the wolfSSH_CleanPath() function in wolfSSH. An authenticated remote attacker can trigger the issue via crafted SCP path input containing '/./' sequences, resulting in a heap over read by 1 byte.

CVE-2025-13912 Low · 1.0 CWE-203 Dec 11, 2025

Potential non-constant time compiled code with Clang LLVM

Multiple constant-time implementations in wolfSSL before version 5.8.4 may be transformed into non-constant-time binary by LLVM optimizations, which can potentially result in observable timing discrepancies and lead to information disclosure through timing side-channel attacks.

CVE-2025-12889 Medium · 5.4 CWE-20 Nov 21, 2025

TLS 1.2 Client Can Downgrade Digest Used

With TLS 1.2 connections a client can use any digest, specifically a weaker digest that is supported, rather than those in the CertificateRequest.

CVE-2025-12888 High · 7.5 CWE-203 Nov 21, 2025

Constant Time Issue with Xtensa-based ESP32 and X22519

Vulnerability in X25519 constant-time cryptographic implementations due to timing side channels introduced by compiler optimizations and CPU architecture limitations, specifically with the Xtensa-based ESP32 chips. If targeting Xtensa it is recommended to use the low memory implementations of X25519, which is now turned on as the default for Xtensa.

CVE-2025-11936 Medium · 5.3 CWE-20 Nov 21, 2025

Potential DoS Vulnerability through Multiple KeyShareEntry with Same Group in TLS 1.3 ClientHello

Improper input validation in the TLS 1.3 KeyShareEntry parsing in wolfSSL v5.8.2 on multiple platforms allows a remote unauthenticated attacker to cause a denial-of-service by sending a crafted ClientHello message containing duplicate KeyShareEntry values for the same supported group, leading to excessive CPU and memory consumption during ClientHello processing.

CVE-2025-11934 Low · 2.7 CWE-20 Nov 21, 2025

Improper Validation of Signature Algorithm Used in TLS 1.3 CertificateVerify

Improper input validation in the TLS 1.3 CertificateVerify signature algorithm negotiation in wolfSSL 5.8.2 and earlier on multiple platforms allows for downgrading the signature algorithm used. For example when a client sends ECDSA P521 as the supported signature algorithm the server previously could respond as ECDSA P256 being the accepted signature algorithm and the connection would continue with using ECDSA P256, if the client supports ECDSA P256.

CVE-2025-11932 Medium · 4.3 CWE-203 Nov 21, 2025

Timing Side-Channel in PSK Binder Verification

The server previously verified the TLS 1.3 PSK binder using a non-constant time method which could potentially leak information about the PSK binder

CVE-2025-11933 Medium · 6.5 CWE-20 Nov 21, 2025

DoS Vulnerability in wolfSSL TLS 1.3 CKS Extension

Improper Input Validation in the TLS 1.3 CKS extension parsing in wolfSSL 5.8.2 and earlier on multiple platforms allows a remote unauthenticated attacker to potentially cause a denial-of-service via a crafted ClientHello message with duplicate CKS extensions.

CVE-2025-11931 High · 8.2 CWE-191 Nov 21, 2025

Integer Underflow Leads to Out-of-Bounds Access in XChaCha20-Poly1305 Decrypt

Integer Underflow Leads to Out-of-Bounds Access in XChaCha20-Poly1305 Decrypt. This issue is hit specifically with a call to the function wc_XChaCha20Poly1305_Decrypt() which is not used with TLS connections, only from direct calls from an application.