Remote crash via ChaCha AEAD length underflow
Published Apr 9, 2026 · Updated Apr 9, 2026
Integer underflow in the wolfSSL packet sniffer 5.9.0 and earlier allows remote attackers to crash an inspecting program via malformed TLS records. ChachaAEADDecrypt subtracts the authentication-tag size from a shorter 16-bit input length without first rejecting the record, wrapping the result and passing a large length to AEAD decryption. The packet sniffer must inspect attacker-influenced Application Data; the resulting out-of-bounds read interrupts only that process.
Summary
What happened
Integer underflow in the wolfSSL packet sniffer 5.9.0 and earlier allows remote attackers to crash an inspecting program via malformed TLS records. ChachaAEADDecrypt subtracts the authentication-tag size from a shorter 16-bit input length without first rejecting the record, wrapping the result and passing a large length to AEAD decryption. The packet sniffer must inspect attacker-influenced Application Data; the resulting out-of-bounds read interrupts only that process.
The record
- CVE
- CVE-2026-5778
- Published
- Apr 9, 2026
- Updated
- Apr 9, 2026
- Vendor
- wolfSSL
- Product
- wolfSSL
- Classifications
- CWE-191, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 9, 2026CVE publishedPublication date reported by the CVE source.
- Apr 9, 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.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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