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Fencer Intel
high 7.5

CVE-2020-19861 json

When a zone file in ldns 1.7.1 is parsed, the function ldns_nsec3_salt_data is too trusted for the length value obtained from the zone file.

published 4y ago modified 4mo ago also EUVD-2020-11757

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.5%
EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits
0
none known

Summary

When a zone file in ldns 1.7.1 is parsed, the function ldns_nsec3_salt_data is too trusted for the length value obtained from the zone file. When the memcpy is copied, the 0xfe - ldns_rdf_size(salt_rdf) byte data can be copied, causing heap overflow information leakage.

Patch / fix

  • ldns Debian 14, Debian 13, Debian 12 1.8.1-1

debian advisories DEBIAN-CVE-2020-19861

  • ldns Ubuntu 18.04 LTS 1.7.0-3ubuntu4.1
  • ldns Ubuntu Pro 16.04 LTS 1.6.17-8ubuntu0.1+esm1
  • ldns Ubuntu Pro 20.04 LTS 1.7.0-4.1ubuntu1+esm1
  • ldns Ubuntu Pro 22.04 LTS 1.7.1-2ubuntu4+esm1

ubuntu advisories UBUNTU-CVE-2020-19861

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • ldns SLE Real Time 15 SP2, SLE Module for Development Tools 15 SP3, SLE Module for Basesystem 15 SP3 1.7.0-4.6.1

suse advisories SUSE-SU-2022:0675-1

  • ldns openSUSE Tumbleweed 1.8.1-1.1
  • ldns openSUSE Leap 15.3 1.7.0-4.6.1

opensuse advisories openSUSE-SU-2024:11802-1openSUSE-SU-2022:0675-1

Is CVE-2020-19861 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-19861 updated cvss 0.0

ldns: Heap out-of-bound read vulnerability in ldns_nsec3_salt_data function

  • Red Hat Enterprise Linux 6 ldns, ldns-python Red Hat Enterprise Linux 7 ldns, ldns-python Red Hat Enterprise Linux 8 ldns, perl-ldns, ldns-utils, python3-ldns Red Hat Enterprise Linux 9 ldns, perl-ldns, ldns-utils, python3-ldns
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.49% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/NLnetLabs/ldns/issues/51 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:P/I:N/A:N

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.