CVE-2011-4528 [Medium] | Denial of Service in Unbound

CVE-2011-4528 is rated Moderate Risk (50.8/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.91%). EPSS rose +1.01% over the last day, indicating growing attacker interest. Review affected assets and schedule remediation.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2025-11-18	1.90%	2.91%	+1.01%
2	2025-03-30	2.78%	1.90%	-0.88%
3	2025-03-29	—	2.78%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2025-11-18

1.90%

2.91%

+1.01%

2025-03-30

2.78%

1.90%

-0.88%

2025-03-29

—

2.78%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.0	2.0	MEDIUM	`AV:N/AC:L/Au:N/C:N/I:N/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:N) No confidentiality impact. Integrity impact (I:N) No integrity impact. Availability impact (A:P) Partial availability impact.	10.0	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.0

2.0

MEDIUM

AV:N/AC:L/Au:N/C:N/I:N/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:N): No confidentiality impact.
Integrity impact (I:N): No integrity impact.
Availability impact (A:P): Partial availability impact.

10.0

2.9

[email protected]

OS Trackers for CVE-2011-4528

vendor	priority	summary	link
`debian`	medium	CVE-2011-4528 medium 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-2011-4528
`gentoo`	normal	CVE-2011-4528: 1 GLSA(s) (201311-18), 1 atom(s) (net-dns/unbound); latest impact normal.	https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2011-4528
`ubuntu`	medium	CVE-2011-4528 medium priority: Ubuntu including 1 source packages (unbound), 6 status rows across 6 suites (hardy, lucid, maverick, natty, oneiric, upstream): released 4, DNE 1, not-affected 1.	https://ubuntu.com/security/CVE-2011-4528

Affected software / configurations for CVE-2011-4528

Vendor	Product	Version	Raw CPE
unbound	unbound	<= 1.4.13	cpe:2.3:a:unbound:unbound::::::::
unbound	unbound	0.0	cpe:2.3:a:unbound:unbound:0.0:::::::*
unbound	unbound	0.1	cpe:2.3:a:unbound:unbound:0.1:::::::*
unbound	unbound	0.2	cpe:2.3:a:unbound:unbound:0.2:::::::*
unbound	unbound	0.3	cpe:2.3:a:unbound:unbound:0.3:::::::*
unbound	unbound	0.4	cpe:2.3:a:unbound:unbound:0.4:::::::*
unbound	unbound	0.5	cpe:2.3:a:unbound:unbound:0.5:::::::*
unbound	unbound	0.6	cpe:2.3:a:unbound:unbound:0.6:::::::*
unbound	unbound	0.7	cpe:2.3:a:unbound:unbound:0.7:::::::*
unbound	unbound	0.7.1	cpe:2.3:a:unbound:unbound:0.7.1:::::::*
unbound	unbound	0.7.2	cpe:2.3:a:unbound:unbound:0.7.2:::::::*
unbound	unbound	0.8	cpe:2.3:a:unbound:unbound:0.8:::::::*
unbound	unbound	0.09	cpe:2.3:a:unbound:unbound:0.09:::::::*
unbound	unbound	0.10	cpe:2.3:a:unbound:unbound:0.10:::::::*
unbound	unbound	0.11	cpe:2.3:a:unbound:unbound:0.11:::::::*
unbound	unbound	1.0.0	cpe:2.3:a:unbound:unbound:1.0.0:::::::*
unbound	unbound	1.0.1	cpe:2.3:a:unbound:unbound:1.0.1:::::::*
unbound	unbound	1.0.2	cpe:2.3:a:unbound:unbound:1.0.2:::::::*
unbound	unbound	1.1.0	cpe:2.3:a:unbound:unbound:1.1.0:::::::*
unbound	unbound	1.1.1	cpe:2.3:a:unbound:unbound:1.1.1:::::::*
unbound	unbound	1.2.0	cpe:2.3:a:unbound:unbound:1.2.0:::::::*
unbound	unbound	1.2.1	cpe:2.3:a:unbound:unbound:1.2.1:::::::*
unbound	unbound	1.3.0	cpe:2.3:a:unbound:unbound:1.3.0:::::::*
unbound	unbound	1.3.1	cpe:2.3:a:unbound:unbound:1.3.1:::::::*
unbound	unbound	1.3.2	cpe:2.3:a:unbound:unbound:1.3.2:::::::*
unbound	unbound	1.3.3	cpe:2.3:a:unbound:unbound:1.3.3:::::::*
unbound	unbound	1.3.4	cpe:2.3:a:unbound:unbound:1.3.4:::::::*
unbound	unbound	1.4.0	cpe:2.3:a:unbound:unbound:1.4.0:::::::*
unbound	unbound	1.4.1	cpe:2.3:a:unbound:unbound:1.4.1:::::::*
unbound	unbound	1.4.2	cpe:2.3:a:unbound:unbound:1.4.2:::::::*
unbound	unbound	1.4.3	cpe:2.3:a:unbound:unbound:1.4.3:::::::*
unbound	unbound	1.4.4	cpe:2.3:a:unbound:unbound:1.4.4:::::::*
unbound	unbound	1.4.5	cpe:2.3:a:unbound:unbound:1.4.5:::::::*
unbound	unbound	1.4.6	cpe:2.3:a:unbound:unbound:1.4.6:::::::*
unbound	unbound	1.4.7	cpe:2.3:a:unbound:unbound:1.4.7:::::::*
unbound	unbound	1.4.8	cpe:2.3:a:unbound:unbound:1.4.8:::::::*
unbound	unbound	1.4.9	cpe:2.3:a:unbound:unbound:1.4.9:::::::*
unbound	unbound	1.4.10	cpe:2.3:a:unbound:unbound:1.4.10:::::::*
unbound	unbound	1.4.11	cpe:2.3:a:unbound:unbound:1.4.11:::::::*
unbound	unbound	1.4.12	cpe:2.3:a:unbound:unbound:1.4.12:::::::*
unbound	unbound	1.4.14	cpe:2.3:a:unbound:unbound:1.4.14:rc1::::::

References for CVE-2011-4528

URL	Tags
http://lists.fedoraproject.org/pipermail/package-announce/2012-January/071525.html
http://lists.fedoraproject.org/pipermail/package-announce/2012-January/071535.html
http://osvdb.org/77909
http://secunia.com/advisories/47326
http://unbound.nlnetlabs.nl/downloads/CVE-2011-4528.txt	Patch Vendor Advisory
http://www.debian.org/security/2011/dsa-2370
http://www.kb.cert.org/vuls/id/209659	Patch Third Party Advisory US Government Resource

URL

CVE-2011-4528

Exploit prediction scoring system (EPSS) score for CVE-2011-4528

Common vulnerability scoring system (CVSS) metrics for CVE-2011-4528

Weakness enumeration for CVE-2011-4528

OS Trackers for CVE-2011-4528

NVD evaluator notes for CVE-2011-4528

Affected software / configurations for CVE-2011-4528

References for CVE-2011-4528