CVE-2015-4000: The TLS protocol 1.2 and earlier, when a DHE_EXPORT ciphersuite is enabled on a server but not on a client, do

This week

LOW 3.7REMOTEWATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2015-4000 is a low-severity flaw (CVSS 3.7) affecting openssl, ubuntu linux, hp-ux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

EPSS top 1%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	3.7 (Low)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	99.9% (top 1%)
CISA exploited list	No
Weakness	CWE-310, CWE-295
Published	2015-05-21
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: canonical · debian · hp · ibm · openssl · oracle

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2015-05-21 00:59 UTCPublished CVE record published
2026-06-17 00:26 UTCUpdated Record last modified

openssl openssl UPGRADE

Affected: >= 1.0.1 and <= 1.0.1m · >= 1.0.2 and <= 1.0.2a · <= 1.0.1m

Fixed in: newer than 1.0.2a

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy openssl || rpm -q openssl || openssl --version

2. UPGRADE to newer than 1.0.2a (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade openssl

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade openssl

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

canonical ubuntu linux MITIGATE

Affected: 12.04 · 14.04 · 14.10 · 15.04

Fixed in: no fixed release known

Safe to downgrade to: a release before 12.04

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

hp hp-ux MITIGATE

Affected: b.11.31

Fixed in: no fixed release known

Safe to downgrade to: a release before b.11.31

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

ibm content manager DOWNGRADE

Affected: 8.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.5

1. Check installed version

apt-cache policy content-manager || rpm -q content-manager || content-manager --version

2. No fixed release: DOWNGRADE to a release before 8.5 (Debian / Ubuntu)

apt-cache madison content-manager sudo apt install content-manager=<VERSION_BEFORE_8.5> sudo apt-mark hold content-manager

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list content-manager sudo dnf downgrade content-manager-<VERSION_BEFORE_8.5> sudo dnf versionlock add content-manager

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

oracle jrockit DOWNGRADE

Affected: r28.3.6

Fixed in: no fixed release known

Safe to downgrade to: a release before r28.3.6

1. Check installed version

apt-cache policy jrockit || rpm -q jrockit || jrockit --version

2. No fixed release: DOWNGRADE to a release before r28.3.6 (Debian / Ubuntu)

apt-cache madison jrockit sudo apt install jrockit=<VERSION_BEFORE_r28.3.6> sudo apt-mark hold jrockit

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list jrockit sudo dnf downgrade jrockit-<VERSION_BEFORE_r28.3.6> sudo dnf versionlock add jrockit

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

debian debian linux MITIGATE

Affected: 7.0 · 8.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Metasploit: SSL/TLS Version Detection

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2015-4000?

openssl: upgrade to newer than 1.0.2a; ubuntu linux: mitigate or apply the listed mitigation; hp-ux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2015-4000 being exploited?

CVE-2015-4000 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2015-4000 affect?

CVE-2015-4000 affects openssl, ubuntu linux, hp-ux. Severity is low (CVSS 3.7). 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 rewrit

How urgent is CVE-2015-4000?

Priority 53/100. EPSS top 1%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

OpenSSL vulnerabilities · Ubuntu vulnerabilities · Debian vulnerabilities

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References

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