CVE-2026-5187

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First, a bounds check only validates one available slot before writing two OID arc values (out[0] and out[1]), enabling a 2-byte out-of-bounds write when outSz equals 1. Second, multiple callers pass sizeof(decOid) (64 bytes on 64-bit platforms) instead of the element count MAX_OID_SZ (32), causing the function to accept crafted OIDs with 33 or more arcs that write past the end of the allocated buffer.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>Two potential heap out-of-bounds write locations existed in DecodeObjectId() in wolfcrypt/src/asn.c. First, a bounds check only validates one available slot before writing two OID arc values (out[0] and out[1]), enabling a 2-byte out-of-bounds write when outSz equals 1. Second, multiple callers pass sizeof(decOid) (64 bytes on 64-bit platforms) instead of the element count MAX_OID_SZ (32), causing the function to accept crafted OIDs with 33 or more arcs that write past the end of the allocated buffer.<br></p>"}]}], "references": [{"url": "https://github.com/wolfSSL/wolfssl", "name": "wolfSSL GitHub Repository"}], "metrics": [{"format": "CVSS", "scenarios": [{"lang": "en", "value": "GENERAL"}], "cvssV4_0": {"attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "PRESENT", "privilegesRequired": "LOW", "userInteraction": "NONE", "vulnConfidentialityImpact": "NONE", "subConfidentialityImpact": "NONE", "vulnIntegrityImpact": "LOW", "subIntegrityImpact": "NONE", "vulnAvailabilityImpact": "LOW", "subAvailabilityImpact": "NONE", "exploitMaturity": "NOT_DEFINED", "Safety": "NOT_DEFINED", "Automatable": "NOT_DEFINED", "Recovery": "NOT_DEFINED", "valueDensity": "NOT_DEFINED", "vulnerabilityResponseEffort": "NOT_DEFINED", "providerUrgency": "NOT_DEFINED", "version": "4.0", "baseSeverity": "LOW", "baseScore": 2.3, "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N"}}], "configurations": [{"lang": "en", "value": "Bug 1 (off-by-one) affects any code calling DecodeObjectId() with an output buffer of size 1. Bug 2 (sizeof mismatch) is reachable via network when wolfSSL is compiled with HAVE_OID_DECODING or WOLFSSL_ASN_PRINT, and WC_ASN_UNKNOWN_EXT_CB is enabled with a registered unknown extension callback.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>Bug 1 (off-by-one) affects any code calling DecodeObjectId() with an output buffer of size 1. Bug 2 (sizeof mismatch) is reachable via network when wolfSSL is compiled with HAVE_OID_DECODING or WOLFSSL_ASN_PRINT, and WC_ASN_UNKNOWN_EXT_CB is enabled with a registered unknown extension callback.</p>"}]}], "workarounds": [{"lang": "en", "value": "Do not enable WC_ASN_UNKNOWN_EXT_CB or do not register an unknown extension callback if not required. This mitigates the network-reachable variant (Bug 2) but does not address Bug 1.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>Do not enable WC_ASN_UNKNOWN_EXT_CB or do not register an unknown extension callback if not required. This mitigates the network-reachable variant (Bug 2) but does not address Bug 1.</p>"}]}], "solutions": [{"lang": "en", "value": "Fix Bug 1: Add a bounds check requiring at least 2 output slots before writing the first OID arc split (y == 0 case). Fix Bug 2: Change callers to pass the element count (MAX_OID_SZ) instead of sizeof(decOid) as the output buffer size parameter.", "supportingMedia": [{"type": "text/html", "base64": false, "value": "<p>Fix Bug 1: Add a bounds check requiring at least 2 output slots before writing the first OID arc split (y == 0 case). Fix Bug 2: Change callers to pass the element count (MAX_OID_SZ) instead of sizeof(decOid) as the output buffer size parameter.</p>"}]}], "credits": [{"lang": "en", "value": "ytsun, Independent Security Researcher", "type": "finder"}], "source": {"discovery": "UNKNOWN"}, "x_generator": {"engine": "Vulnogram 1.0.1"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-5187", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-04-14T14:03:11.195034Z"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-04-14T14:04:53.585Z"}}]}}

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{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "generic", "value": "[0,5.9.0]"}}], "enrichment": {"confidence": 100.0, "confidence_source": "matching", "scores": [{"score": 100.0, "source": "matching"}]}, "original": {"product": "wolfSSL", "source": "cna", "vendor": "wolfSSL"}, "product": "wolfssl", "vendor": "wolfssl"}], "analysis": {"en": {"generated_at": "2026-04-09T21:50:36.706131+00:00", "value": {"mitigation_remediation": ["Apply the latest wolfSSL patch that adds the required bounds check for two output slots and changes callers to use MAX_OID_SZ instead of sizeof(decOid).", "If the patch cannot be applied immediately, disable the WC_ASN_UNKNOWN_EXT_CB feature or avoid registering an unknown extension callback so the network\u2011reachable variant of the overflow cannot be triggered."], "summary": {"action": "Apply Patch", "impact": "Memory Corruption via Heap Out\u2011of\u2011Bounds Write"}, "threat_synthesis": {"affected_systems": "The issue resides in the wolfSSL cryptographic library; it applies to any application that links against wolfSSL versions containing the legacy DecodeObjectId implementation within wolfcrypt/src/asn.c. Specific version ranges are not enumerated in the CNA data, so all releases compiled with this code are potentially affected.", "description_and_impact": "DecodeObjectId() in wolfSSL performs an incorrect bounds check, writing two Object Identifier components into an output buffer that is only sized for one. A second flaw allows callers to pass the size of the structure instead of the intended element count, enabling an attacker to provide a crafted ASN.1 value with 33 or more arcs that overflows the buffer. The resulting heap write can corrupt adjacent memory, potentially causing crashes or unpredictable behavior; no direct remote code execution path is documented for this flaw.", "risk_and_exploitability": "The CVSS score of 2.3 indicates a low severity, and the vulnerability is not listed in CISA\u2019s KEV catalog. The exploit requires a crafted ASN.1 payload that the application processes; if the WC_ASN_UNKNOWN_EXT_CB callback is enabled, the payload could be transmitted over a network, giving a remote attacker a network\u2011reachable vector. Absent that option, exploitation remains limited to local or application\u2011level input. Overall risk is low to moderate pending the presence of the callback and the ability to supply the malicious ASN.1 data."}}}}, "created": "2026-04-10T08:38:41.999515+00:00", "updated": "2026-04-10T09:29:25.183688+00:00", "vendors": ["wolfssl", "wolfssl$PRODUCT$wolfssl"]}