What is CVE-2016-2851?

CVE-2016-2851 is a critical-severity vulnerability in Cypherpunks Libotr, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 9.8/10. Published 2016-04-07.

How severe is CVE-2016-2851?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Is CVE-2016-2851 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Buffer overflow in Cypherpunks Libotr

CVE-2016-2851

Integer overflow in proto.c in libotr before 4.1.1 on 64-bit platforms allows remote attackers to cause a denial of service (memory corruption and application crash) or execute arbitrary code via a series of large OTR messages, which triggers a heap-based buffer overflow.

Vulnerability class: Buffer Overflow

Published 2016-04-07 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.254 (97.9th percentile), scored 2026-09-30.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 98th percentile — 97.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.254 · newest: 0.254 · change: 0.000

Affected products

Cypherpunks Libotr
Debian Linux — versions 7.0, 8.0
openSUSE Leap — versions 42.1
openSUSE — versions 13.2

Weakness classification (CWE)

CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer

Public proof-of-concept exploits

ARPSyndicate/cvemon

References

www.ubuntu.com/usn/USN-2926-1 (vendor-advisory, Third Party Advisory)
www.securityfocus.com/archive/1/537745/100/0/threaded (mailing-list, Third Party Advisory)
www.debian.org/security/2016/dsa-3512 (vendor-advisory, Third Party Advisory)
security.gentoo.org/glsa/201701-10 (vendor-advisory, Third Party Advisory)
www.exploit-db.com/exploits/39550/ (VDB Entry, Third Party Advisory, exploit)
www.securityfocus.com/bid/84285 (VDB Entry, Third Party Advisory, vdb-entry)
seclists.org/fulldisclosure/2016/Mar/21 (mailing-list, Exploit, Mailing List, Third Party Advisory)
www.x41-dsec.de/lab/advisories/x41-2016-001-libotr/ (Exploit)
lists.opensuse.org/opensuse-security-announce/2016-03/msg00021.html (vendor-advisory, Mailing List)
lists.cypherpunks.ca/pipermail/otr-users/2016-March/002581.html (mailing-list, Exploit)

Frequently asked questions

What is CVE-2016-2851?: CVE-2016-2851 is a critical-severity vulnerability in Cypherpunks Libotr, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. CVSS score: 9.8/10. Published 2016-04-07.
How severe is CVE-2016-2851?: Critical severity. CVSS v3 base score is 9.8 out of 10.
Is CVE-2016-2851 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.