What’s Vulnerable › Vulnerabilities
CVE-2021-3716
- Severity: low (CVSS 3.1 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 0.6% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2022-03-02 · updated 2026-06-17
- Weakness: CWE-924
Description
A flaw was found in nbdkit due to to improperly caching plaintext state across the STARTTLS encryption boundary. A MitM attacker could use this flaw to inject a plaintext NBD_OPT_STRUCTURED_REPLY before proxying everything else a client sends to the server, potentially leading the client to terminate the NBD session. The highest threat from this vulnerability is to system availability.
Affected products
- nbdkit: from 1.11.8 before 1.24.6; from 1.25.1 before 1.26.5; from 1.27.1 before 1.27.6 — fixed in 1.24.6, 1.26.5, 1.27.6
- Red Hat Enterprise Linux: 8.0
How to fix
Upgrade to a fixed version: nbdkit 1.24.6, 1.26.5, 1.27.6. Check the vendor advisory for mitigations.
References
- https://bugzilla.redhat.com/show_bug.cgi?id=1994695
- https://gitlab.com/nbdkit/nbdkit/-/commit/09a13dafb7bb3a38ab52eb5501cba786365ba7fd
- https://gitlab.com/nbdkit/nbdkit/-/commit/6c5faac6a37077cf2366388a80862bb00616d0d8
- https://listman.redhat.com/archives/libguestfs/2021-August/msg00083.html
- https://www.openwall.com/lists/oss-security/2021/08/18/2
- https://bugzilla.redhat.com/show_bug.cgi?id=1994695
- https://gitlab.com/nbdkit/nbdkit/-/commit/09a13dafb7bb3a38ab52eb5501cba786365ba7fd
- https://gitlab.com/nbdkit/nbdkit/-/commit/6c5faac6a37077cf2366388a80862bb00616d0d8
- https://listman.redhat.com/archives/libguestfs/2021-August/msg00083.html
- https://www.openwall.com/lists/oss-security/2021/08/18/2
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