CVE-2016-2181

The Anti-Replay feature in the DTLS implementation in OpenSSL before 1.1.0 mishandles early use of a new epoch number in conjunction with a large sequence number, which allows remote attackers to cause a denial of service (false-positive packet drops) via spoofed DTLS records, related to rec_layer_d1.c and ssl3_record.c.

Published: 2016-09-16 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2016-2181 is rated Moderate Risk (62.5/100): CVSS High severity, with high exploitation likelihood (EPSS 22.63%, 97th percentile). EPSS ranks this CVE among the most likely to be exploited in the near term. High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2016-2181

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 24.27% 22.63% -1.63%
2 2026-04-21 23.03% 24.27% +1.24%
3 2026-03-04 — 23.03% —

Full EPSS history (48 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2016-2181

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.0 HIGH
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
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]

Weakness enumeration for CVE-2016-2181

OS Trackers for CVE-2016-2181

vendor priority summary link
debian not yet assigned CVE-2016-2181 not yet assigned priority: Debian including 1 source packages (openssl), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2016-2181
redhat medium — https://access.redhat.com/security/cve/CVE-2016-2181
suse medium CVE-2016-2181 severity moderate: SUSE including 475 source package names (amazon/suse-sles-15-sp1-chost-byos-v20210304-hvm-ssd-x86_64, amazon/suse-sles-15-sp1-chost-byos-v20220127-hvm-ssd-x86_64, …), 837 product×package rows across 107 product lines (HPE Helion OpenStack 8, Image SLES12-SP5-Azure-SAP-BYOS, … (107 product lines)): Fixed 465, Known Not Affected 215, Known Affected 157. https://www.suse.com/security/cve/CVE-2016-2181/
ubuntu low CVE-2016-2181 low priority: Ubuntu including 2 source packages (openssl, openssl098), 20 status rows across 10 suites (artful, bionic, cosmic, disco, precise, trusty, upstream, xenial, yakkety, zesty): released 10, DNE 8, ignored 1, needs-triage 1. https://ubuntu.com/security/CVE-2016-2181

Affected software / configurations for CVE-2016-2181

Vendor Product Version Raw CPE
openssl openssl 1.0.1 cpe:2.3:a:openssl:openssl:1.0.1:*:*:*:*:*:*:*
openssl openssl 1.0.1a cpe:2.3:a:openssl:openssl:1.0.1a:*:*:*:*:*:*:*
openssl openssl 1.0.1b cpe:2.3:a:openssl:openssl:1.0.1b:*:*:*:*:*:*:*
openssl openssl 1.0.1c cpe:2.3:a:openssl:openssl:1.0.1c:*:*:*:*:*:*:*
openssl openssl 1.0.1d cpe:2.3:a:openssl:openssl:1.0.1d:*:*:*:*:*:*:*
openssl openssl 1.0.1e cpe:2.3:a:openssl:openssl:1.0.1e:*:*:*:*:*:*:*
openssl openssl 1.0.1f cpe:2.3:a:openssl:openssl:1.0.1f:*:*:*:*:*:*:*
openssl openssl 1.0.1g cpe:2.3:a:openssl:openssl:1.0.1g:*:*:*:*:*:*:*
openssl openssl 1.0.1h cpe:2.3:a:openssl:openssl:1.0.1h:*:*:*:*:*:*:*
openssl openssl 1.0.1i cpe:2.3:a:openssl:openssl:1.0.1i:*:*:*:*:*:*:*
openssl openssl 1.0.1j cpe:2.3:a:openssl:openssl:1.0.1j:*:*:*:*:*:*:*
openssl openssl 1.0.1k cpe:2.3:a:openssl:openssl:1.0.1k:*:*:*:*:*:*:*
openssl openssl 1.0.1l cpe:2.3:a:openssl:openssl:1.0.1l:*:*:*:*:*:*:*
openssl openssl 1.0.1m cpe:2.3:a:openssl:openssl:1.0.1m:*:*:*:*:*:*:*
openssl openssl 1.0.1n cpe:2.3:a:openssl:openssl:1.0.1n:*:*:*:*:*:*:*
openssl openssl 1.0.1o cpe:2.3:a:openssl:openssl:1.0.1o:*:*:*:*:*:*:*
openssl openssl 1.0.1p cpe:2.3:a:openssl:openssl:1.0.1p:*:*:*:*:*:*:*
openssl openssl 1.0.1q cpe:2.3:a:openssl:openssl:1.0.1q:*:*:*:*:*:*:*
openssl openssl 1.0.1r cpe:2.3:a:openssl:openssl:1.0.1r:*:*:*:*:*:*:*
openssl openssl 1.0.1s cpe:2.3:a:openssl:openssl:1.0.1s:*:*:*:*:*:*:*
openssl openssl 1.0.1t cpe:2.3:a:openssl:openssl:1.0.1t:*:*:*:*:*:*:*
openssl openssl 1.0.2 cpe:2.3:a:openssl:openssl:1.0.2:*:*:*:*:*:*:*
openssl openssl 1.0.2a cpe:2.3:a:openssl:openssl:1.0.2a:*:*:*:*:*:*:*
openssl openssl 1.0.2b cpe:2.3:a:openssl:openssl:1.0.2b:*:*:*:*:*:*:*
openssl openssl 1.0.2c cpe:2.3:a:openssl:openssl:1.0.2c:*:*:*:*:*:*:*
openssl openssl 1.0.2d cpe:2.3:a:openssl:openssl:1.0.2d:*:*:*:*:*:*:*
openssl openssl 1.0.2e cpe:2.3:a:openssl:openssl:1.0.2e:*:*:*:*:*:*:*
openssl openssl 1.0.2f cpe:2.3:a:openssl:openssl:1.0.2f:*:*:*:*:*:*:*
openssl openssl 1.0.2g cpe:2.3:a:openssl:openssl:1.0.2g:*:*:*:*:*:*:*
openssl openssl 1.0.2h cpe:2.3:a:openssl:openssl:1.0.2h:*:*:*:*:*:*:*
oracle linux 6 cpe:2.3:o:oracle:linux:6:*:*:*:*:*:*:*
oracle linux 7 cpe:2.3:o:oracle:linux:7:*:*:*:*:*:*:*

References for CVE-2016-2181

URL Tags
http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10759 Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2016-09/msg00022.html
http://lists.opensuse.org/opensuse-security-announce/2016-09/msg00023.html
http://lists.opensuse.org/opensuse-security-announce/2016-09/msg00024.html
http://lists.opensuse.org/opensuse-security-announce/2016-09/msg00031.html
http://lists.opensuse.org/opensuse-security-announce/2016-10/msg00005.html
http://lists.opensuse.org/opensuse-security-announce/2016-10/msg00011.html
http://lists.opensuse.org/opensuse-security-announce/2016-10/msg00012.html
http://lists.opensuse.org/opensuse-security-announce/2016-10/msg00029.html
http://lists.opensuse.org/opensuse-security-announce/2017-10/msg00010.html
http://lists.opensuse.org/opensuse-security-announce/2017-10/msg00011.html
http://lists.opensuse.org/opensuse-security-announce/2018-02/msg00032.html
http://rhn.redhat.com/errata/RHSA-2016-1940.html
http://seclists.org/fulldisclosure/2017/Jul/31
http://www-01.ibm.com/support/docview.wss?uid=swg21995039 Third Party Advisory
http://www.debian.org/security/2016/dsa-3673
http://www.huawei.com/en/psirt/security-advisories/huawei-sa-20170322-01-openssl-en
http://www.oracle.com/technetwork/security-advisory/cpuapr2018-3678067.html
http://www.oracle.com/technetwork/security-advisory/cpujan2018-3236628.html
http://www.oracle.com/technetwork/security-advisory/cpujul2017-3236622.html
http://www.oracle.com/technetwork/security-advisory/cpuoct2016-2881722.html Third Party Advisory
http://www.oracle.com/technetwork/security-advisory/cpuoct2017-3236626.html
http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2016-3090545.html Third Party Advisory
http://www.oracle.com/technetwork/topics/security/ovmbulletinoct2016-3090547.html Third Party Advisory
http://www.securityfocus.com/bid/92982 Third Party Advisory VDB Entry
http://www.securitytracker.com/id/1036690
http://www.splunk.com/view/SP-CAAAPSV Third Party Advisory
http://www.splunk.com/view/SP-CAAAPUE Third Party Advisory
http://www.ubuntu.com/usn/USN-3087-1
http://www.ubuntu.com/usn/USN-3087-2
https://bto.bluecoat.com/security-advisory/sa132 Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-412672.pdf
https://git.openssl.org/?p=openssl.git%3Ba=commit%3Bh=1fb9fdc3027b27d8eb6a1e6a846435b070980770
https://kb.pulsesecure.net/articles/Pulse_Security_Advisories/SA40312 Third Party Advisory
https://kc.mcafee.com/corporate/index?page=content&id=SB10215
https://security.FreeBSD.org/advisories/FreeBSD-SA-16:26.openssl.asc
https://support.f5.com/csp/article/K59298921
https://www.arista.com/en/support/advisories-notices/security-advisories/1749-security-advisory-24
https://www.tenable.com/security/tns-2016-16 Third Party Advisory
https://www.tenable.com/security/tns-2016-20
https://www.tenable.com/security/tns-2016-21
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