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CVE-2026-6681— PKCS#7 decode ignores caller output buffer size, writing past buffer bounds

Quick assessment

Affected
wolfSSL wolfSSL
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

wolfSSL是wolfSSL公司开源的一个针对嵌入式系统开发人员使用的小的、可移植的嵌入式SSL编程库。 wolfSSL存在缓冲区错误漏洞，该漏洞源于PKCS#7解码路径忽略调用者提供的输出缓冲区大小，允许解码内容写入超出缓冲区边界。

AI Predicted 8.1 Difficulty: Moderate EPSS 0.26% · P18

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 1

VendorProduct Version RangeStatus
wolfSSL wolfSSL 3.10.0≤ 5.9.0 affected
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I. Basic Information for CVE-2026-6681

Vulnerability Information
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Vulnerability Title
PKCS#7 decode ignores caller output buffer size, writing past buffer bounds
Source: CVE Program / CVE List V5
Vulnerability Description
The PKCS#7 decode path ignores the caller-supplied output buffer size (outputSz), allowing decoded content to be written past the bounds of the provided buffer. This affects wolfSSL 5.9.0 and earlier and was fixed in the 5.9.1 release.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:A/AC:L/AT:P/PR:L/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/U:Clear
Source: CVE Program / CVE List V5
Vulnerability Type
跨界内存写
Source: CVE Program / CVE List V5
Vulnerability Title
wolfSSL 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
wolfSSL是wolfSSL公司开源的一个针对嵌入式系统开发人员使用的小的、可移植的嵌入式SSL编程库。 wolfSSL存在缓冲区错误漏洞，该漏洞源于PKCS#7解码路径忽略调用者提供的输出缓冲区大小，允许解码内容写入超出缓冲区边界。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
wolfSSL wolfSSL 3.10.0 ~ 5.9.0 -

II. Public POCs for CVE-2026-6681

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III. Intelligence Information for CVE-2026-6681

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Patches & Fixes for CVE-2026-6681 (1)

Vendor Pages for CVE-2026-6681 (1)

Same Patch Batch · wolfSSL · 2026-06-25 · 32 CVEs total

CVE-2026-6329 PKCS#12 MAC verification uses attacker-controlled comparison length
CVE-2026-55958 Renesas TSIP TLS 1.3 transcript buffer out-of-bounds write in tsip_StoreMessage
CVE-2026-55960 Un-negotiated Raw Public Key (RFC 7250) accepted in place of X.509, bypassing chain valida
CVE-2026-55967 AES-GCM streaming APIs do not reject >64 GiB cumulative single messages, enabling counter
CVE-2026-55961 wolfSSL_PKCS7_verify() reports success for degenerate (certs-only) PKCS#7 with no signer
CVE-2026-55962 TLS 1.3 post-handshake authentication: server accepts Finished without client Certificate/
CVE-2026-55964 Chain intermediate CA:TRUE without keyCertSign accepted as a signing CA (temporary CA exem
CVE-2026-8720 HMAC-BLAKE2 final discards message when key length exceeds block size
CVE-2026-12340 Out-of-bounds heap read in SM2/SM3 certificate Subject Key Identifier computation
CVE-2026-10512 X25519 x86_64 assembly final reduction leaves non-canonical field element
CVE-2026-10097 ML-KEM-1024 x64 AVX2 incomplete cipher text comparison enables IND-CCA2 break and static p
CVE-2026-10098 OCSP CertID serial-number length-confusion in wolfSSL_OCSP_resp_find_status
CVE-2026-10592 Wildcard DNS SAN bypasses CA name-constraint checks
CVE-2026-11310 X.509 trust-chain bypass in wolfSSL_X509_verify_cert() via untrusted intermediate anchorin
CVE-2026-11703 Missing SNI/ALPN binding on stateful (session-ID) TLS session resumption
CVE-2026-11999 X.509 trust-chain bypass via path-depth exhaustion in wolfSSL_X509_verify_cert()
CVE-2026-7532 iPAddress name constraints not enforced when WOLFSSL_IP_ALT_NAME is undefined
CVE-2026-6679 DTLS 1.3 ACK serialization heap buffer overflow via integer truncation
CVE-2026-6094 Heap buffer overread in wc_PKCS7_DecodeEnvelopedData parsing crafted PKCS7 EnvelopedData
CVE-2026-6731 X.509 name constraint bypass via Subject CN treated as a DNS name

Showing top 20 of 32 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: wolfSSL
Same vendor: wolfSSL
Same weakness: CWE-787

V. Comments for CVE-2026-6681

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