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Fencer Vulns
high 7.5

CVE-2019-25036 json

Unbound before 1.9.5 allows an assertion failure and denial of service in synth_cname.

published 2021-04-27 5 y ago modified 2026-06-17 4 mo ago also EUVD-2019-11486

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.9%
EPSS 1.9% chance of exploitation in 30 days, percentile 80%
public exploits
0
none known

Summary

Unbound before 1.9.5 allows an assertion failure and denial of service in synth_cname. NOTE: The vendor disputes that this is a vulnerability. Although the code may be vulnerable, a running Unbound installation cannot be remotely or locally exploited

Patch / fix

  • nlnetlabs unbound 1.9.5
  • unbound Debian 14, Debian 13, Debian 12 1.9.6-1

debian advisories DEBIAN-CVE-2019-25036

  • unbound Ubuntu 18.04 LTS 1.6.7-1ubuntu2.4
  • unbound Ubuntu 20.04 LTS 1.9.4-2ubuntu1.2

ubuntu advisories UBUNTU-CVE-2019-25036

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

  • unbound RHEL 8 1.7.3-15.el8
  • unbound-libs RHEL 8 1.7.3-15.el8
  • python3-unbound RHEL 8 1.7.3-15.el8
  • unbound RHEL 8.2 EUS 1.7.3-12.el8_2
  • unbound-libs RHEL 8.2 EUS 1.7.3-12.el8_2
  • python3-unbound RHEL 8.2 EUS 1.7.3-12.el8_2

red hat advisories RHSA-2022:0632RHSA-2021:1853

  • unbound SLES 15 SP2-BCL, SLES 15 SP1-BCL, SLE Real Time 15 SP2 +14 more 1.6.8-10.6.1
  • unbound SLES for SAP 15, SLES 15-LTSS, SLE High Performance Computing 15-LTSS +1 more 1.6.8-3.9.1

suse advisories SUSE-SU-2022:0176-2SUSE-SU-2022:0301-1SUSE-SU-2022:0176-1

  • unbound openSUSE Leap 15.3 1.6.8-10.6.1

opensuse advisories openSUSE-SU-2022:0176-1

  • unbound Rocky Linux 8 1.7.3-15.el8

rocky linux advisories RLSA-2021:1853

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-2019-25036 updated cvss 9.8

unbound: assertion failure and denial of service in synth_cname

  • Red Hat Enterprise Linux 6 unbound, unbound-libs, unbound-python Red Hat Enterprise Linux 7 unbound, unbound-libs, unbound-python
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) unbound 1.7.3-15.el8, unbound-libs 1.7.3-15.el8, python3-unbound 1.7.3-15.el8
    fixed: vendor fix RHSA-2021:1853
  • Red Hat Enterprise Linux AppStream EUS (v. 8.2) unbound 1.7.3-12.el8_2, unbound-libs 1.7.3-12.el8_2, python3-unbound 1.7.3-12.el8_2
    fixed: vendor fix RHSA-2022:0632
  • Red Hat Enterprise Linux 9 unbound, unbound-libs, unbound-dracut, python3-unbound
    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

1.93% chance of exploitation in the next 30 days, higher than 80% of all scored CVEs (FIRST EPSS, 2026-11-08).

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:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Classification

Weakness

References

Sources

Fencer Vulns 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.