CVE-2015-2156: Netty before 3.9.8.Final, 3.10.x before 3.10.3.Final, 4.0.x before 4.0.28.Final, and 4.1.x before 4.1.0.Beta5

This month

HIGH 7.5REMOTEUPGRADEDOWNGRADEDOWNGRADE

CVE-2015-2156 is a high-severity flaw (CVSS 7.5) affecting netty, play framework, play framework. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Netty before 3.9.8.Final, 3.10.x before 3.10.3.Final, 4.0.x before 4.0.28.Final, and 4.1.x before 4.1.0.Beta5 and Play Framework 2.x before 2.3.9 might allow remote attackers to bypass the httpOnly flag on cookies and obtain sensitive information by leveraging improper validation of cookie name and value characters.

Why this priority

High severity
EPSS top 7%: very likely to be exploited
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	5.2% (top 7%)
CISA exploited list	No
Weakness	CWE-20
Published	2017-10-18
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: lightbend · netty · playframework

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

Am I affected?

Timeline

2017-10-18 15:29 UTCPublished CVE record published
2026-06-17 00:23 UTCUpdated Record last modified

netty netty UPGRADE

Affected: <= 3.9.7 · 3.10.0 · 3.10.1 · 3.10.2 · 4.0.0 · 4.0.1 · 4.0.2 · 4.0.3

Fixed in: newer than 3.9.7

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 3.9.7 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade netty

Note

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

lightbend play framework DOWNGRADE

Affected: 2.0 rc3 · 2.0 rc4 · 2.0 rc5 · 2.0.2 · 2.0.2 rc1 · 2.0.2 rc2 · 2.0.3 · 2.0.3 rc1

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0

1. Check installed version

apt-cache policy play-framework || rpm -q play-framework || play-framework --version

2. No fixed release: DOWNGRADE to a release before 2.0 (Debian / Ubuntu)

apt-cache madison play-framework sudo apt install play-framework=<VERSION_BEFORE_2.0> sudo apt-mark hold play-framework

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

dnf --showduplicates list play-framework sudo dnf downgrade play-framework-<VERSION_BEFORE_2.0> sudo dnf versionlock add play-framework

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.

playframework play framework DOWNGRADE

Affected: 2.0 · 2.0 beta · 2.0 rc1 · 2.0 rc2 · 2.0.1 · 2.1.1 2.9.x-backport · 2.1.1 rc1-2.9.x-backport · 2.1.1 rc2

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0

1. Check installed version

apt-cache policy play-framework || rpm -q play-framework || play-framework --version

2. No fixed release: DOWNGRADE to a release before 2.0 (Debian / Ubuntu)

apt-cache madison play-framework sudo apt install play-framework=<VERSION_BEFORE_2.0> sudo apt-mark hold play-framework

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

dnf --showduplicates list play-framework sudo dnf downgrade play-framework-<VERSION_BEFORE_2.0> sudo dnf versionlock add play-framework

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.

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-2015-2156?

netty: upgrade to newer than 3.9.7; play framework: downgrade or apply the listed mitigation; play framework: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2015-2156 being exploited?

CVE-2015-2156 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-2015-2156 affect?

CVE-2015-2156 affects netty, play framework, play framework. Severity is high (CVSS 7.5). Netty before 3.9.8.Final, 3.10.x before 3.10.3.Final, 4.0.x before 4.0.28.Final, and 4.1.x before 4.1.0.Beta5 and Play Framework 2.x before 2.3.9 might allow remote attackers to bypass the httpOnly flag on cookies and obtain sensitive infor

How urgent is CVE-2015-2156?

Priority 54/100. High severity; EPSS top 7%: very likely to be exploited; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-42587 HIGH 7.5 UPGRADE Netty is an asynchronous, event-driven network application framework
CVE-2026-42584 HIGH 7.3 UPGRADE Netty is an asynchronous, event-driven network application framework
CVE-2026-42583 HIGH 7.5 UPGRADE Netty is an asynchronous, event-driven network application framework
CVE-2026-42580 MEDIUM 6.5 UPGRADE Netty is an asynchronous, event-driven network application framework
CVE-2026-42585 MEDIUM 6.5 UPGRADE Netty is an asynchronous, event-driven network application framework

References

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