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WolfsslApplication

CVE-2019-15651

CRITICAL · 9.8 CVSS v3.0 Published 2019-08-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
wolfSSL 4.1.0 has a one-byte heap-based buffer over-read in DecodeCertExtensions in wolfcrypt/src/asn.c because reading the ASN_BOOLEAN byte is mishandled for a crafted DER certificate in GetLength_ex.

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 confidence

wolfSSL 4.1.0 contains a one-byte heap-based buffer over-read vulnerability in the DecodeCertExtensions function within wolfcrypt/src/asn.c. The vulnerability occurs when parsing DER certificates where the ASN_BOOLEAN byte length calculation in GetLength_ex is mishandled, allowing an attacker to read one byte beyond the allocated buffer boundary by supplying a crafted DER certificate.

MitigationUpgrade to a patched version of wolfSSL. Until then, avoid processing untrusted DER certificates with affected wolfSSL installations to reduce exposure.

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
WolfsslApplication
Affected:= 4.1.0

CVSS 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:3.0/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 checks

Work through these to decide whether this CVE applies to you.

  1. Check installed wolfSSL version
    Run 'wolfssl version' or check the version string in your build, typically accessible via wolfSSL_GetVersion() API or looking at libwolfssl version define
    Affected if The version reported is exactly 4.1.0
  2. Verify DER certificate parsing is in use
    Inspect application code for calls to wolfSSL_d2i_X509(), d2i_X509(), or similar DER-to-X509 parsing functions that process certificate data
    Affected if Your application loads or parses DER-encoded certificates from external or untrusted sources
  3. Check for presence of vulnerable asn.c
    Locate wolfcrypt/src/asn.c in your wolfSSL installation and verify the file exists; the vulnerable DecodeCertExtensions function is contained within it
    Affected if The asn.c source file is present and being used for ASN.1 parsing
  4. Look for heap corruption indicators
    Run application under memory debugging tools such as valgrind or AddressSanitizer while processing DER certificates to detect buffer over-read warnings
    Affected if Memory diagnostics report a one-byte read beyond buffer boundary during certificate extension parsing

You are affected if you run wolfSSL version 4.1.0 and process DER certificates from untrusted sources using the ASN.1 parsing code.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade to a patched version of wolfSSL. Until then, avoid processing untrusted DER certificates with affected wolfSSL installations to reduce exposure.

Recommended fix Moderate confidence

wolfSSL 4.2.0 or later

  1. 1. Identify systems or applications using wolfSSL version 4.1.0
  2. 2. Download wolfSSL version 4.2.0 or later from the official wolfSSL repository (https://github.com/wolfSSL/wolfssl)
  3. 3. Review the wolfSSL changelog for version 4.2.0 to confirm the vulnerability fix is included
  4. 4. Compile and install the updated wolfSSL library
  5. 5. Rebuild and redeploy any applications that link against the wolfSSL library
  6. 6. Verify the new version is correctly installed by checking the library version at runtime
  7. 7. Test the application functionality to ensure the upgrade does not break existing features
Caveat Newer versions may include API changes; review release notes and test thoroughly before production deployment

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Wolfssl Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing12.0 h
  • Review / QA6.0 h
30.0 hours of engineering $5,120
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-15651 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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  • No spam, self-promotion, credentials, or personal data