CVE-2026-5187
CVE-2026-5187 is a critical-severity vulnerability in Wolfssl with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-122.
Key facts
- Severity: Critical (CVSS 3.x base score 9.8)
- CVSS v4: 2.3
- EPSS exploit prediction: 0% (20th percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-21068
- Weakness: CWE-122
- Affected product: Wolfssl
- Published:
- Last modified:
Description
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.
Frequently asked questions
- What is CVE-2026-5187?
- 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.
- How severe is CVE-2026-5187?
- CVE-2026-5187 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2026-5187 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (20th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-5187?
- CVE-2026-5187 affects Wolfssl. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-5187?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- Does CVE-2026-5187 have an EU (EUVD) identifier?
- Yes. CVE-2026-5187 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-21068.
- When was CVE-2026-5187 published?
- CVE-2026-5187 was published on 2026-04-09 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:*
More vulnerabilities in Wolfssl
- CVE-2026-7531 — Critical (CVSS 9.8): Use-after-free in PQC hybrid key-share handling. This is an incomplete-fix follow-up to CVE-2026-5460 (released in…
- CVE-2026-5264 — Critical (CVSS 9.8): Heap buffer overflow in DTLS 1.3 ACK message processing. A remote attacker can send a crafted DTLS 1.3 ACK message that…
- CVE-2026-4395 — Critical (CVSS 9.8): Heap-based buffer overflow in the KCAPI ECC code path of wc_ecc_import_x963_ex() in wolfSSL wolfcrypt allows a remote…
- CVE-2026-3849 — Critical (CVSS 9.8): Stack Buffer Overflow in wc_HpkeLabeledExtract via Oversized ECH Config. A vulnerability existed in wolfSSL 5.8.4 ECH…
- CVE-2026-3549 — Critical (CVSS 9.8): Heap Overflow in TLS 1.3 ECH parsing. An integer underflow existed in ECH extension parsing logic when calculating a…
- CVE-2026-3548 — Critical (CVSS 9.8): Two buffer overflow vulnerabilities existed in the wolfSSL CRL parser when parsing CRL numbers: a heap-based buffer…
Other CWE-122 (Heap-based Buffer Overflow) vulnerabilities
- CVE-2026-46752 — Critical (CVSS 10.0): Redis Lua HEAP overflow in cjson library vulnerability in Apache Kvrocks. This issue affects Apache Kvrocks: from…
- CVE-2026-24822 — Critical (CVSS 10.0): Out-of-bounds Write, Heap-based Buffer Overflow vulnerability in ttttupup wxhelper (src modules). This vulnerability is…
- CVE-2025-23123 — Critical (CVSS 10.0): A malicious actor with access to the management network could execute a remote code execution (RCE) by exploiting a…
- CVE-2022-34819 — Critical (CVSS 10.0): A vulnerability has been identified in SIMATIC CP 1242-7 V2 (All versions < V3.3.46), SIMATIC CP 1243-1 (All versions <…
- CVE-2026-44050 — Critical (CVSS 9.9): A heap-based buffer overflow in the CNID daemon comm_rcv() function in Netatalk 2.0.0 through 4.4.2 allows a remote…
- CVE-2026-49841 — Critical (CVSS 9.8): FreeSWITCH is a Software Defined Telecom Stack enabling the digital transformation from proprietary telecom switches to…
Browse all CWE-122 (Heap-based Buffer Overflow) vulnerabilities →