How severe is CVE-2015-4000?

CVE-2015-4000 has a CVSS score of 3.7/10, rated LOW. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2015-4000?

Affected package information for CVE-2015-4000 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2015-4000?

No fixed release is recorded for CVE-2015-4000 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

How do I detect CVE-2015-4000 in my code and dependencies?

Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

How do I mitigate CVE-2015-4000 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2015-4000 actively exploited in the wild?

Yes. There are 3 known exploit references for CVE-2015-4000, including 2 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2015-4000?

CVE-2015-4000 has an EPSS (Exploit Prediction Scoring System) score of 99.9%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

What type of vulnerability is CVE-2015-4000?

CVE-2015-4000 is classified as CWE-310 (CWE-310), CWE-295 (CWE-295). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2015-4000 published, and has it been updated?

CVE-2015-4000 was published on May 21, 2015 and was last updated on April 16, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🛡️

Not in CISA KEV

LOW severity

CVE-2015-4000 — Red Hat

LOW

CVE-2015-4000 is a low-severity (CVSS 3.7) CWE-310 vulnerability. 3 public exploit references exist, so weaponization risk is real. No vendor fix is recorded yet; mitigation options are listed below.

Published

May 21, 2015

Updated

Apr 16, 2026

Affected

25 products

Patched

See advisory

Exploits

3 known

Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2015-4000.

EPSS Exploitation Probability

via FIRST.org ↗

99.9%probability of exploitation in next 30 days

Very High Risk0.00%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2015-4000 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 394,803 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Counts from FIRST.org, log-scaled.

Description

The TLS protocol 1.2 and earlier, when a DHE_EXPORT ciphersuite is enabled on a server but not on a client, does not properly convey a DHE_EXPORT choice, which allows man-in-the-middle attackers to conduct cipher-downgrade attacks by rewriting a ClientHello with DHE replaced by DHE_EXPORT and then rewriting a ServerHello with DHE_EXPORT replaced by DHE, aka the "Logjam" issue.

Affected Products

25 products · 42 configurations

iphone osapple

≤ 8.3

range

mac os xapple

≤ 10.10.3

range

Application

safariapple

all

ubuntu linuxcanonical

4 versions

12.0414.0414.1015.04

debian linuxdebian

2 versions

7.08.0

Application

chromegoogle

all

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

The TLS protocol 1.2 and earlier, when a DHE_EXPORT ciphersuite is enabl…

github.comGithubApr 2021

The TLS protocol 1.2 and earlier, when a DHE_EXPORT ciphersuite is enabl…

github.comMetasploitNov 2022

Detection & mitigation playbook

Vulnerability

Detect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Remediation status
No fixed release is recorded for CVE-2015-4000 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

This issue affects the version of openssl and nss libraries as shipped with Red Hat Enterprise Linux 4, 5, 6 and 7. More information about this flaw is available at: https://bugzilla.redhat.com/show_bug.cgi?id=1223211#c4 and https://bugzilla.redhat.com/show_bug.cgi?id=1223211#c5. Red Hat Enterprise Linux 4 is in…

Product	Fixed in	Advisory
Oracle Java for Red Hat Enterprise Linux 5	`java-1.7.0-oracle-1:1.7.0.85-1jpp.1.el5_11`	RHSA-2015:1242
Oracle Java for Red Hat Enterprise Linux 5	`java-1.6.0-sun-1:1.6.0.101-1jpp.1.el5_11`	RHSA-2015:1243
Oracle Java for Red Hat Enterprise Linux 6	`java-1.8.0-oracle-1:1.8.0.51-1jpp.2.el6_6`	RHSA-2015:1241
Red Hat Enterprise Linux 5	`openssl-0:0.9.8e-36.el5_11`	RHSA-2015:1197
Red Hat Enterprise Linux 5	`java-1.7.0-openjdk-1:1.7.0.85-2.6.1.3.el5_11`	RHSA-2015:1230
Red Hat Enterprise Linux 5	`java-1.6.0-openjdk-1:1.6.0.36-1.13.8.1.el5_11`	RHSA-2015:1526
Red Hat Enterprise Linux 5 Supplementary	`java-1.6.0-ibm-1:1.6.0.16.7-1jpp.1.el5`	RHSA-2015:1486
Red Hat Enterprise Linux 5 Supplementary	`java-1.7.0-ibm-1:1.7.0.9.10-1jpp.2.el5`	RHSA-2015:1488

UbuntuLOW

2696-1Ubuntu USN-2706-1Ubuntu USN-2673-1Ubuntu USN-2696-1Ubuntu USN-2656-1Ubuntu USN-2656-2Ubuntu

Frequently Asked Questions

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