CVE-2019-16748
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn wolfSSL through 4.1.0, there is a missing sanity check of memory accesses in parsing ASN.1 certificate data while handshaking. Specifically, there is a one-byte heap-based buffer over-read in CheckCertSignature_ex in wolfcrypt/src/asn.c.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidencewolfSSL versions through 4.1.0 have a missing sanity check in the CheckCertSignature_ex function in wolfcrypt/src/asn.c when parsing ASN.1 certificate data during TLS handshaking. This results in a one-byte heap-based buffer over-read, potentially allowing attackers to cause denial of service or potentially achieve remote code execution via malicious certificate data.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 4.1.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check if wolfSSL is installedLook for wolfSSL libraries or headers on the system. Common library names include libwolfssl.so, libwolfssl.a, or files containing 'wolfssl' in /usr/lib, /usr/local/lib, or similar directories. Also check for wolfssl header files.Affected if wolfSSL libraries or development files are present on the system
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Determine the installed wolfSSL versionRun 'wolfssl version' if the CLI tool is available, or check the library version via 'ldconfig -p | grep wolfssl' and then examine the library file metadata. If source code is available, check the version defined in version.h or configure.ac.Affected if The version is 4.1.0 or lower, or if the version cannot be determined and wolfSSL is present
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Verify if TLS certificate verification is in useReview application code or configuration that uses wolfSSL to determine if TLS connections with client or server certificate verification are enabled. The vulnerability triggers during ASN.1 certificate signature parsing, which occurs when certificates are being verified.Affected if TLS certificate verification is enabled and wolfSSL <= 4.1.0 is in use
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Inspect the vulnerable source fileIf source code is available, examine wolfcrypt/src/asn.c and locate the CheckCertSignature_ex function. Look for the presence of sanity/bounds checks before the certificate signature comparison logic.Affected if The CheckCertSignature_ex function lacks proper bounds checking before the buffer over-read occurs (the fix adds sanity checks for ASN.1 certificate signature parsing)
A system is affected if wolfSSL version 4.1.0 or earlier is installed and TLS certificate verification is being used, as the missing sanity check in ASN.1 certificate signature parsing triggers during the TLS handshake process.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade wolfSSL to version 4.1.0 or later, which includes the missing bounds/sanity checks in ASN.1 certificate signature parsing. If upgrading is not immediately feasible, consider restricting accepted certificate sources to trusted CAs and monitoring for anomalous TLS handshakes.
wolfSSL 4.2.0 or later
- Upgrade wolfSSL to version 4.2.0 or later to resolve the out-of-bounds read vulnerability in CheckCertSignature_ex
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing8.0 h
- Review / QA3.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2019-16748 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2019-16748 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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