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CVE-2020-35857

Stack consumption in trust-dns-server

7.5 HighFix available

An issue was discovered in the trust-dns-server crate before 0.18.1 for Rust. DNS MX and SRV null targets are mishandled, causing stack consumption.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

1.46%Up 1.0 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 7.5

An issue was discovered in the trust-dns-server crate before 0.18.1 for Rust. DNS MX and SRV null targets are mishandled, causing stack consumption.

Record
CVE-2020-35857
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness
CWE-400
Updated
2026-11-02
CVE List No score

An issue was discovered in the trust-dns-server crate before 0.18.1 for Rust. DNS MX and SRV null targets are mishandled, causing stack consumption.

Record
CVE-2020-35857
Updated
2026-11-02
EUVDEUVD-2021-1559 No score

An issue was discovered in the trust-dns-server crate before 0.18.1 for Rust. DNS MX and SRV null targets are mishandled, causing stack consumption.

Record
EUVD-2021-1559
Updated
2026-11-03
GitHub AdvisoriesGHSA-4cww-f7w5-x525 7.5

Stack consumption in trust-dns-server

There's a stack overflow leading to a crash and potential DOS when processing additional records for return of MX or SRV record types from the server. This is only possible when a zone is configured with a null target for MX or SRV records. Prior to 0.16.0 the additional record processing was not supported by trust-dns-server. There Are no known issues with upgrading from 0.16 or 0.17 to 0.18.1. The remidy should be to upgrade to 0.18.1. If unable to do so, MX, SRV or other record types with a target to the null type, should be avoided.

Record
GHSA-4cww-f7w5-x525
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-400
Updated
2026-11-02
OSVGHSA-4cww-f7w5-x525 7.5

Stack consumption in trust-dns-server

There's a stack overflow leading to a crash and potential DOS when processing additional records for return of MX or SRV record types from the server. This is only possible when a zone is configured with a null target for MX or SRV records. Prior to 0.16.0 the additional record processing was not supported by trust-dns-server. There Are no known issues with upgrading from 0.16 or 0.17 to 0.18.1. The remidy should be to upgrade to 0.18.1. If unable to do so, MX, SRV or other record types with a target to the null type, should be avoided.

Record
GHSA-4cww-f7w5-x525
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-400
Updated
2026-11-02
OSVRUSTSEC-2020-0001 7.5

Stack overflow when resolving additional records from MX or SRV null targets

There's a stack overflow leading to a crash and potential DOS when processing additional records for return of MX or SRV record types from the server.

This is only possible when a zone is configured with a null target for MX or SRV records, i.e. '.'.

Example effected zone record:

no-service 86400 IN MX 0 .

Prior to 0.16.0 the additional record processing was not supported by trust-dns-server. There Are no known issues with upgrading from 0.16 or 0.17 to 0.18.1. The remidy should be to upgrade to 0.18.1. If unable to do so, MX, SRV or other record types with a target to the null type, should be avoided.

Record
RUSTSEC-2020-0001
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
trust-dns-server
crates.io
0.16.0 up to 0.18.1
0.18.1

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-35857 is a high vulnerability (CVSS 7.5) in Trust-dns-server Project Trust-dns-server, published January 6, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.46%, the 73rd percentile. Fixed in trust-dns-server 0.18.1.

References

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