EUVD-2026-39572
GHSA-xpf5-wwvx-w945
Severity by source
CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:N/VI:L/VA:L/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:Clear
Local vector with high complexity because exploitation requires influencing application-layer API arguments; no confidentiality impact; bounded write yields only low integrity and availability impact.
Primary rating from Vendor (wolfSSL).
CVSS VectorVendor: wolfSSL
Lifecycle Timeline
2DescriptionCVE.org
Out-of-bounds write in SetSuitesHashSigAlgo when processing an oversized signature algorithms list, allowing a write past the bounds of the destination buffer.
AnalysisAI
Out-of-bounds write in wolfSSL's SetSuitesHashSigAlgo function corrupts memory when an application passes an oversized signature algorithms list to the wolfSSL_CTX_set1_sigalgs_list or wolfSSL_set1_sigalgs_list APIs, writing past the end of the internal suites buffer (CWE-787). All wolfSSL versions prior to the bounds-check fix in PR #10204 are affected; the CVSS 4.0 score of 2.0 reflects a local-only vector, high complexity, and constrained impact limited to low integrity and availability degradation within the consuming process. No public exploit has been identified and this vulnerability is not listed in CISA KEV, indicating no confirmed active exploitation at time of analysis.
Technical ContextAI
wolfSSL is a lightweight, portable C-language TLS/SSL library widely used in embedded systems, RTOS environments, and IoT devices, identified by CPE cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*. The vulnerable function SetSuitesHashSigAlgo in src/internal.c parses a colon-delimited string of signature algorithm names into an internal fixed-size buffer indexed by the variable idx. Prior to the fix, the function failed to verify that idx had not exceeded WOLFSSL_MAX_SIGALGO before writing each entry, constituting a classic CWE-787 out-of-bounds write. The PR #10204 fix introduces a pre-write bounds check: it computes the bytes needed per entry (2 normally, 4 for RSA-PSS under TLS 1.3 when WC_RSA_PSS and WOLFSSL_TLS13 are both defined) and breaks out of the parsing loop when (word32)idx + needed would exceed WOLFSSL_MAX_SIGALGO. The companion test in tests/api.c confirms the trigger: constructing a list with WOLFSSL_MAX_SIGALGO + 1 entries now returns WOLFSSL_FAILURE rather than writing out of bounds.
RemediationAI
Apply the upstream fix from GitHub PR #10204 (https://github.com/wolfSSL/wolfssl/pull/10204) by upgrading to the wolfSSL release that incorporates this change; consult https://www.wolfssl.com/docs/security-vulnerabilities/ for the official patched version once tagged. The patch is an upstream fix available via PR/commit; a released patched version is not independently confirmed from available data, so monitor the vendor advisory page for confirmation. As a compensating control prior to patching, application developers can validate that signature algorithm list strings passed to wolfSSL_CTX_set1_sigalgs_list and wolfSSL_set1_sigalgs_list contain no more than WOLFSSL_MAX_SIGALGO entries before invoking these APIs; this requires application-layer changes and may not be feasible for all integrators or where the input source is not under developer control. Applications that hardcode a fixed, short signature algorithm list are not exploitable and require no immediate action.
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Same weakness CWE-787 – Out-of-bounds Write
View allSame technique Buffer Overflow
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External POC / Exploit Code
Leaving vuln.today