Low

X.509 date buffer overflow in wolfSSL_X509_notAfter / wolfSSL_X509_notBefore

IdentifiersCVE-2026-5448CWE-122· Heap-based Buffer Overflow

CVE-2026-5448 is a buffer overflow in wolfSSL’s OpenSSL compatibility layer affecting the wolfSSL_X509_notAfter() and wolfSSL_X509_notBefore() APIs. When an application directly invokes these functions on a crafted X.509 certificate, malformed date fields can trigger a small heap-based overflow during parsing. The issue has been described as a 2-byte heap overflow. The vulnerability is limited to these compatibility-layer APIs and does not affect wolfSSL’s normal TLS handshake or certificate verification operations.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can corrupt adjacent heap memory in the calling process when it parses attacker-controlled X.509 certificate date fields through the affected APIs. Based on the available information, the practical impact is memory corruption and potential process instability or crash in applications that directly use wolfSSL_X509_notAfter() or wolfSSL_X509_notBefore(). The provided content does not establish reliable remote code execution, and normal TLS or certificate verification paths are not affected.

Mitigation

If you can’t patch tonight, do this now.

Do not pass untrusted or attacker-supplied certificates to wolfSSL_X509_notAfter() or wolfSSL_X509_notBefore() in vulnerable builds. Prefer patched wolfSSL releases and, where feasible, rely on wolfSSL’s native TLS and certificate verification paths rather than direct use of the affected OpenSSL compatibility APIs. Additional input validation or isolation around certificate parsing may reduce exposure, but the primary mitigation is upgrading.

Remediation

Patch, then assume compromise.

Upgrade to wolfSSL 5.9.1 or later, which includes the fix for CVE-2026-5448. If immediate upgrade is not possible, modify the application to avoid direct use of wolfSSL_X509_notAfter() and wolfSSL_X509_notBefore() on untrusted certificates until the patched version is deployed.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

WolfsslWolfsslapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

4 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

4 SOURCESView more in app

anthropicNews

May 22, 2026

Anthropic's coordinated vulnerability disclosure dashboard

A medium-severity heap buffer overflow in wolfSSL affecting wolfSSL_X509_notAfter / wolfSSL_X509_notBefore.

bugflationNews

May 20, 2026

Anthropic CVD dashboard reveals fixed Mythos Preview open-source findings - Bugflation

A vendor-confirmed vulnerability in wolfSSL disclosed through Anthropic’s coordinated vulnerability disclosure pipeline and marked as patched and fixed.

What this page doesn’t show

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Exposure mapping

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Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity2