Memory corruption via undersized CRL number buffers
Published Mar 19, 2026 · Updated Mar 19, 2026
Buffer overflows in the wolfSSL CRL parser before 5.9.0 allow attackers to corrupt memory by loading a crafted CRL number. The heap path converts the number to hex in a buffer sized for binary octets, while ParseCRL_Extensions passes oversized integers to sp_read_unsigned_bin on a 64-byte stack object. Only CRL-enabled builds that load an untrusted CRL are exposed; the out-of-bounds writes can crash the process or corrupt adjacent memory.
Summary
What happened
Buffer overflows in the wolfSSL CRL parser before 5.9.0 allow attackers to corrupt memory by loading a crafted CRL number. The heap path converts the number to hex in a buffer sized for binary octets, while ParseCRL_Extensions passes oversized integers to sp_read_unsigned_bin on a 64-byte stack object. Only CRL-enabled builds that load an untrusted CRL are exposed; the out-of-bounds writes can crash the process or corrupt adjacent memory.
The record
- CVE
- CVE-2026-3548
- Published
- Mar 19, 2026
- Updated
- Mar 19, 2026
- Vendor
- wolfSSL
- Product
- wolfSSL
- Classifications
- CWE-787, CWE-122
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 19, 2026CVE publishedPublication date reported by the CVE source.
- Mar 19, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <5.9.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Oversized CRL number AddressSanitizer reproducerproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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