CVE-2016-2183: DES/3DES Birthday Bound Flaw Enables Cleartext Recovery (Sweet32)

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 18 September 2026. Confidence: medium.

high priorityCVSS 7.5 with network reachability and high confidentiality impact, plus a very high EPSS score, though exploitation requires capturing a long-duration session and the flaw is not in KEV.

What it is

DES and Triple DES ciphers used in TLS, SSH, IPSec and other protocols have a birthday bound of roughly four billion blocks, allowing a birthday attack against long-duration encrypted sessions. An attacker who can capture enough ciphertext from a single long-lived session can recover cleartext data, as demonstrated against HTTPS using Triple DES in CBC mode (Sweet32).

Impact

An attacker gains partial recovery of cleartext from the affected session, exposing sensitive data carried over it. The CVSS vector shows confidentiality impact only, with no integrity or availability effect.

Attack surface

Reachable remotely over the network (AV:N) with no privileges and no user interaction required, per the CVSS vector. The attacker must be positioned to observe a long-duration session's ciphertext, such as a network man-in-the-middle.

Exploitation

Not listed in CISA KEV and no ransomware associations are recorded, but EPSS is very high at 0.957 (99.9th percentile), indicating strong predicted exploitation activity. Reference tags are advisory and mailing-list entries only, with no public exploit tag supplied.

What to do

• Patch or upgrade affected products (OpenSSL, Red Hat JBoss/Enterprise Linux, Python, Node.js, Cisco, Oracle) to versions that disable or deprecate DES/3DES cipher suites.
• Disable DES and Triple DES cipher suites in TLS, SSH and IPSec configurations, preferring AES-based suites.
• Limit session lifetimes and force rekeying so no single session approaches the four-billion-block birthday bound.
• Audit exposed services for 3DES usage and remove it from allowed cipher lists at load balancers and reverse proxies.

Detection

• Search TLS/SSH/IPSec configuration and handshake logs for negotiated DES or 3DES cipher suites.
• Monitor for unusually long-lived encrypted sessions that could accumulate enough blocks for a birthday attack.
• Alert on network captures or IDS signatures referencing Sweet32 or 3DES CBC session traffic.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.