CVE-2016-2181

CVE-2016-2181 is a high-severity vulnerability in Openssl with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 23% places it in the 97th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-189.

Key facts

Description

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.

Frequently asked questions

What is 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.
How severe is CVE-2016-2181?
CVE-2016-2181 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2016-2181 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 23% (97th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-2181?
CVE-2016-2181 primarily affects Openssl. In total, 32 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-2181?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2016-2181 published?
CVE-2016-2181 was published on 2016-09-16 and last updated on 2026-06-17.

References

Affected products (32)

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Threat intelligence

Threat-intel indicators referencing this CVE: