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CVE-2021-3634
CVE ID
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CVE-2021-3634
MITRE ATT&CK
Collection
Command and Control
Credential Access
Defense Evasion
Discovery
Execution
Exfiltration
Impact
Initial Access
Lateral Movement
Persistence
Privilege Escalation
Topic Tags
Description
A flaw has been found in libssh in versions prior to 0.9.6. The SSH protocol keeps track of two shared secrets during the lifetime of the session. One of them is called secret_hash and the other session_id. Initially, both of them are the same, but after key re-exchange, previous session_id is kept and used as an input to new secret_hash. Historically, both of these buffers had shared length variable, which worked as long as these buffers were same. But the key re-exchange operation can also change the key exchange method, which can be based on hash of different size, eventually creating “secret_hash” of different size than the session_id has. This becomes an issue when the session_id memory is zeroed or when it is used again during second key re-exchange.
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CVSS V3 Severity and Metrics
General Information
Vendors
- debian,
- fedoraproject,
- libssh,
- netapp,
- oracle,
- redhat
Products
- cloud backup -,
- debian linux 10.0,
- debian linux 11.0,
- enterprise linux 8.0,
- fedora 33,
- fedora 34,
- fedora 35,
- libssh,
- mysql workbench,
- virtualization 4.0
References
Advisory
Additional Info
Technical Analysis
Report as Exploited in the Wild
CVE ID
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