Cryptolib
CVE-2026-21897
HIGH
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Primary rating from GitHub Advisory · only source for this CVE.
CVSS VectorGitHub Advisory
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Lifecycle Timeline
2DescriptionGitHub Advisory
CryptoLib provides a software-only solution using the CCSDS Space Data Link Security Protocol - Extended Procedures (SDLS-EP) to secure communications between a spacecraft running the core Flight System (cFS) and a ground station. Prior to version 1.4.3, the Crypto_Config_Add_Gvcid_Managed_Parameters function only checks whether gvcid_counter > GVCID_MAN_PARAM_SIZE. As a result, it allows up to the 251st entry, which causes a write past the end of the array, overwriting gvcid_counter located immediately after gvcid_managed_parameters_array[250]. This leads to an out-of-bounds write, and the overwritten gvcid_counter may become an arbitrary value, potentially affecting the parameter lookup/registration logic that relies on it. This issue has been patched in version 1.4.3.
AnalysisAI
Out-of-bounds write in CryptoLib's SDLS-EP implementation allows unauthenticated network attackers to corrupt the gvcid_counter variable by writing beyond array bounds during parameter registration, potentially disrupting spacecraft-to-ground station communications security. Affected systems running CryptoLib versions prior to 1.4.3 are vulnerable to manipulation of parameter lookup logic without authentication or user interaction. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | CryptoLib versions prior to 1.4.3 running on cFS with SDLS-EP protocol enabled. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | CVSS 7.3 (HIGH). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker could exploit this flaw, an out-of-bounds write, and the overwritten gvcid_counter ma. |
| Remediation | Fixed in version 1.4.3.. … Detailed patch versions, workarounds, and compensating controls in full report. |
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Within 7 days: Identify all affected systems and apply vendor patches promptly. …
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