CVE-2016-4456

The "GNUTLS_KEYLOGFILE" environment variable in gnutls 3.4.12 allows remote attackers to overwrite and corrupt arbitrary files in the filesystem.

Published: 2017-08-08 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2016-4456 is rated Moderate Risk (60/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.20%). EPSS rose +1.95% over the last day, indicating growing attacker interest. Review affected assets and schedule 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-2016-4456

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 0.25% 2.20% +1.95%
2 2025-10-07 0.26% 0.25% -0.02%
3 2025-03-30 — 0.26% —

Full EPSS history (7 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2016-4456

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N 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:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:P/A:N 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:P)
Partial integrity impact.
Availability impact (A:N)
No availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2016-4456

OS Trackers for CVE-2016-4456

vendor priority summary link
debian not yet assigned CVE-2016-4456 not yet assigned priority: Debian including 1 source packages (gnutls28), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2016-4456
redhat medium — https://access.redhat.com/security/cve/CVE-2016-4456
suse medium CVE-2016-4456 severity moderate: SUSE including 12 source package names (gnutls, libgnutls-devel, …), 38 product×package rows across 13 product lines (SUSE Linux Enterprise Desktop 12, SUSE Linux Enterprise Desktop 12 SP1, … (13 product lines)): Known Not Affected 38. https://www.suse.com/security/cve/CVE-2016-4456/
ubuntu medium CVE-2016-4456 medium priority: Ubuntu including 1 source packages (gnutls28), 5 status rows across 5 suites (precise, trusty, upstream, wily, xenial): not-affected 3, DNE 1, released 1. https://ubuntu.com/security/CVE-2016-4456

Affected software / configurations for CVE-2016-4456

Vendor Product Version Raw CPE
gnu gnutls 3.4.12 cpe:2.3:a:gnu:gnutls:3.4.12:*:*:*:*:*:*:*

References for CVE-2016-4456

URL Tags
http://www.openwall.com/lists/oss-security/2016/06/07/6 Mailing List Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=1343505 Issue Tracking Third Party Advisory
cvelogic Threat Intelligence