CVE-2026-5187 | wolfSSL up to 5.9.0 wolfcrypt/src/asn.c DecodeObjectId heap-based overflow

VDB-356683 · CVE-2026-5187 · GCVE-0-2026-5187 WOLFSSL UP TO 5.9.0 WOLFCRYPT/SRC/ASN.C DECODEOBJECTID HEAP-BASED OVERFLOW HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 6.1 $0-$5k 1.26 Summaryinfo A vulnerability was found in wolfSSL up to 5.9.0. It has been classified as critical. This affects the function DecodeObjectId of the file wolfcrypt/src/asn.c. This manipulation causes heap-based overflow. This vulnerability appears as CVE-2026-5187. The attack may be initiated remotely. There is no available exploit. Detailsinfo A vulnerability has been found in wolfSSL up to 5.9.0 and classified as critical. Affected by this vulnerability is the function DecodeObjectId of the file wolfcrypt/src/asn.c. The manipulation with an unknown input leads to a heap-based overflow vulnerability. The CWE definition for the vulnerability is CWE-122. A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc(). As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is: 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. The weakness was presented by ytsun. This vulnerability is known as CVE-2026-5187 since 03/30/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 04/09/2026). There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product. Productinfo Name wolfSSL Version 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9.0 License open-source CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA CVSS-B Score: 🔒 CNA CVSS-BT Score: 🔒 CNA Vector: 🔒 CVSSv3info VulDB Meta Base Score: 6.3 VulDB Meta Temp Score: 6.1 VulDB Base Score: 6.3 VulDB Temp Score: 6.1 VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Heap-based overflow CWE: CWE-122 / CWE-119 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: no mitigation known Status: 🔍 0-Day Time: 🔒 Timelineinfo 03/30/2026 CVE reserved 04/09/2026 +10 days Advisory disclosed 04/09/2026 +0 days VulDB entry created 04/09/2026 +0 days VulDB entry last update Sourcesinfo Researcher: ytsun Status: Not defined CVE: CVE-2026-5187 (🔒) GCVE (CVE): GCVE-0-2026-5187 GCVE (VulDB): GCVE-100-356683 Entryinfo Created: 04/09/2026 22:14 Changes: 04/09/2026 22:14 (65) Complete: 🔍 Cache ID: 99:DE2:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸