CVE-2022-0635
Description
An assertion check flaw was found in BIND, with a refactoration of RFC 8198 Aggressive Use of the DNSSEC-Validated Cache feature (synth-from-dnssec). The repeated patterns of specific queries to servers with this feature enabled could cause an INSIST failure in query.c:query_dname, which results in unexpected termination. This flaw allows a remote attacker to use a series of specific queries to trigger a failed assertion check that causes the named process to terminate, leading to a denial of service.
Statement
The vulnerability affects BIND resolvers running 9.18.0 with both dnssec-validation and synth-from-dnssec enabled. (Note that dnssec-validation auto; is the default setting unless configured otherwise in named.conf and that enabling dnssec-validation automatically enables synth-from-dnssec unless explicitly disabled)
This flaw only affects BIND-9.18.0, whereas Red Hat ships BIND-9.16 and lower versions. Therefore, versions of BIND shipped with Red Hat Products are not affected by this flaw.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | 7.5 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
An attacker that can trigger an assert statement can still lead to a denial of service if the relevant code can be triggered by an attacker, and if the scope of the assert() extends beyond the attacker's own session.
Acknowledgements
Upstream acknowledges Vincent Levigneron (AFNIC) as the original reporter.
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