Client crash via flawed KMC metadata tokenization
Published Jan 10, 2026 · Updated Jan 10, 2026
Out-of-bounds read in CryptoLib before 1.4.3 allows remote attackers to crash the client via crafted KMC JSON metadata. In cryptography_encrypt(), manual ptr + strlen(ptr) + 1 advancement after strtok reads one byte beyond short heap and stack buffers. Exploitation requires control of the KMC response through a malicious or compromised server or a man-in-the-middle position; the documented consequence is a client crash.
Summary
What happened
Out-of-bounds read in CryptoLib before 1.4.3 allows remote attackers to crash the client via crafted KMC JSON metadata. In cryptography_encrypt(), manual ptr + strlen(ptr) + 1 advancement after strtok reads one byte beyond short heap and stack buffers. Exploitation requires control of the KMC response through a malicious or compromised server or a man-in-the-middle position; the documented consequence is a client crash.
The record
- CVE
- CVE-2026-21900
- Published
- Jan 10, 2026
- Updated
- Jan 10, 2026
- Vendor
- NASA AMMOS
- Product
- CryptoLib
- Classifications
- CWE-125, CAPEC-540, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 10, 2026CVE publishedPublication date reported by the CVE source.
- Jan 10, 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=< 1.4.3
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
- CryptoLib KMC encrypt metadata ASAN proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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