CVE-2019-25042 [Critical] | Out-of-bounds Write in Unbound

CVE-2019-25042 is rated High Risk (68/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 2.04%). EPSS rose +1.30% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.74%	2.04%	+1.30%
2	2026-01-31	0.95%	0.74%	-0.21%
3	2026-01-21	—	0.95%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.74%

2.04%

+1.30%

2026-01-31

0.95%

0.74%

-0.21%

2026-01-21

—

0.95%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
9.8	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	5.9	[email protected]
7.5	2.0	HIGH	`AV:N/AC:L/Au:N/C:P/I:P/A:P` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	10.0	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

9.8

3.1

CRITICAL

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

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

5.9

[email protected]

7.5

2.0

HIGH

AV:N/AC:L/Au:N/C:P/I:P/A:P Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

10.0

6.4

[email protected]

OS Trackers for CVE-2019-25042

vendor	priority	summary	link
`alpine`	—	CVE-2019-25042: 1 source package rows (unbound); 6 state rows across 6 repos (3.10-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 0, open 6.	https://security.alpinelinux.org/vuln/CVE-2019-25042
`debian`	unimportant	CVE-2019-25042 unimportant priority: Debian including 1 source packages (unbound), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2019-25042
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2019-25042
`suse`	medium	CVE-2019-25042 severity moderate: SUSE including 20 source package names (libunbound-devel-mini-1.6.8-10.6.1, libunbound2-1.6.8-10.6.1, …), 98 product×package rows across 31 product lines (SUSE CaaS Platform 4.0, SUSE Enterprise Storage 6, … (31 product lines)): Fixed 98.	https://www.suse.com/security/cve/CVE-2019-25042/
`ubuntu`	medium	CVE-2019-25042 medium priority: Ubuntu including 1 source packages (unbound), 13 status rows across 13 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, trusty, upstream, xenial): not-affected 10, released 3.	https://ubuntu.com/security/CVE-2019-25042

Affected software / configurations for CVE-2019-25042

Vendor	Product	Version	Raw CPE
nlnetlabs	unbound	< 1.9.5	cpe:2.3:a:nlnetlabs:unbound::::::::
debian	debian_linux	9.0	cpe:2.3:o:debian:debian_linux:9.0:::::::*

References for CVE-2019-25042

URL	Tags
https://lists.debian.org/debian-lts-announce/2021/05/msg00007.html	Mailing List Third Party Advisory
https://ostif.org/our-audit-of-unbound-dns-by-x41-d-sec-full-results/	Not Applicable Third Party Advisory
https://security.netapp.com/advisory/ntap-20210507-0007/	Third Party Advisory

URL

CVE-2019-25042

Exploit prediction scoring system (EPSS) score for CVE-2019-25042

Common vulnerability scoring system (CVSS) metrics for CVE-2019-25042

Weakness enumeration for CVE-2019-25042

OS Trackers for CVE-2019-25042

Affected software / configurations for CVE-2019-25042

References for CVE-2019-25042