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CVE-2019-6475

HIGHCVSS 7.5/10EPSS 1.26%

Last modified

CVE-2019-6475 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. Mirror zones are a BIND feature allowing recursive servers to pre-cache zone data provided by other servers. A mirror zone is similar to a zone of type secondary, except that its data is subject to DNSSEC validation before being used in answers, as if it had been looked up via traditional recursion, and when mirror zone data cannot be validated, BIND falls back to using traditional recursion instead of the mirror zone. EPSS estimates a 1.26% chance of exploitation in the next 30 days.

Description

Mirror zones are a BIND feature allowing recursive servers to pre-cache zone data provided by other servers. A mirror zone is similar to a zone of type secondary, except that its data is subject to DNSSEC validation before being used in answers, as if it had been looked up via traditional recursion, and when mirror zone data cannot be validated, BIND falls back to using traditional recursion instead of the mirror zone. However, an error in the validity checks for the incoming zone data can allow an on-path attacker to replace zone data that was validated with a configured trust anchor with forged data of the attacker's choosing. The mirror zone feature is most often used to serve a local copy of the root zone. If an attacker was able to insert themselves into the network path between a recursive server using a mirror zone and a root name server, this vulnerability could then be used to cause the recursive server to accept a copy of falsified root zone data. This affects BIND versions 9.14.0 up to 9.14.6, and 9.15.0 up to 9.15.4.

Metrics

CVSS 3.1
7.5/10

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

EPSS Probability
1.26%

65.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
IscBind>= 9.14.0, <= 9.14.6
IscBind>= 9.15.0, <= 9.15.4

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2019-6475?
Mirror zones are a BIND feature allowing recursive servers to pre-cache zone data provided by other servers. A mirror zone is similar to a zone of type secondary, except that its data is subject to DNSSEC validation before being used in answers, as if it had been looked up via traditional recursion, and when mirror zone data cannot be validated, BIND falls back to using traditional recursion instead of the mirror zone. However, an error in the validity checks for the incoming zone data can allow an on-path attacker to replace zone data that was validated with a configured trust anchor with forged data of the attacker's choosing. The mirror zone feature is most often used to serve a local copy of the root zone. If an attacker was able to insert themselves into the network path between a recursive server using a mirror zone and a root name server, this vulnerability could then be used to cause the recursive server to accept a copy of falsified root zone data. This affects BIND versions 9.14.0 up to 9.14.6, and 9.15.0 up to 9.15.4.
How severe is CVE-2019-6475?
CVE-2019-6475 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.26% probability of exploitation in the next 30 days.
How do I fix CVE-2019-6475?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST