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GHSA-2c64-vj8g-vwrq
No affected components available
(This advisory is canonically https://advisories.nats.io/CVE/CVE-2020-26892.txt )
Problem Description
NATS nats-server through 2020-10-07 has Incorrect Access Control because of how expired credentials are handled.
The NATS accounts system has expiration timestamps on credentials; the https://github.com/nats-io/jwt library had an API which encouraged misuse and an IsRevoked() method which misused its own API.
A new IsClaimRevoked() method has correct handling and the nats-server has been updated to use this. The old IsRevoked() method now always returns true and other client code will have to be updated to avoid calling it.
The CVE identifier should cover any application using the old JWT API, where the nats-server is one of those applications.
Affected versions
JWT library
- all versions prior to 1.1.0
- fixed after nats-io/jwt PR 103 landed (2020-10-06)
NATS Server
- Version 2 prior to 2.1.9
- 2.0.0 through and including 2.1.8 are vulnerable.
- fixed with nats-io/nats-server PRs 1632, 1635, 1645
Impact
Time-based credential expiry did not work.
Workaround
Have credentials which only expire after fixes can be deployed.
Solution
Upgrade the JWT dependency in any application using it.
Upgrade the NATS server if using NATS Accounts.
Measures severity based on intrinsic characteristics of the vulnerability, independent of environment.
No exploitation activity has been observed at this time. Continue routine monitoring.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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