CVE-20XX-?
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CVE-2021-3634

6.5 MEDIUM 5% exploit odds Fix listed

What it is

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.

At a glance

Exploitability
Can be exploited over the network with a low-privilege account. High risk of service disruption.
Exploit odds
4.7% chance of exploitation in the next 30 days (EPSS).
Fix
A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

  1. PublishedDisclosed publicly on CVE.org and NVD
  2. Last updatedMost recent change to the record

Why it ranks here

Details

Published
Last modified
Exploit probability
4.7% · EPSS, next 30 days
Weakness
CWE-787 · Out-of-bounds write
Record status
Modified

Affected

Attack profile CVSS 3.1 · 6.5

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Raw vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-3634.md and follow it. Check whether this project is affected by CVE-2021-3634. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record