CVE-2017-5340: Zend/zend_hash.c in PHP before 7.0.15 and 7.1.x before 7.1.1 mishandles certain cases that require large array

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CRITICAL 9.8REMOTEUPGRADEMITIGATE

CVE-2017-5340 is a critical-severity flaw (CVSS 9.8) affecting php, clustered data ontap. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Zend/zend_hash.c in PHP before 7.0.15 and 7.1.x before 7.1.1 mishandles certain cases that require large array allocations, which allows remote attackers to execute arbitrary code or cause a denial of service (integer overflow, uninitialized memory access, and use of arbitrary destructor function pointers) via crafted serialized data.

Why this priority

Critical severity
EPSS top 3%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	16.7% (top 3%)
CISA exploited list	No
Weakness	CWE-190
Published	2017-01-11
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: netapp · php

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

Am I affected?

Timeline

2017-01-11 06:59 UTCPublished CVE record published
2026-06-17 01:20 UTCUpdated Record last modified

php php UPGRADE

Affected: >= 7.0.0 and < 7.0.15 · >= 7.1.0 and < 7.1.1

Fixed in: 7.0.15, 7.1.1

Safe to downgrade to: a release before 7.0.0

1. Check installed version

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

2. UPGRADE to 7.0.15 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade php

Note

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

3. If no update is available yet, DOWNGRADE to a release before 7.0.0 (Debian / Ubuntu)

apt-cache madison php sudo apt install php=<VERSION_BEFORE_7.0.0> sudo apt-mark hold php

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list php sudo dnf downgrade php-<VERSION_BEFORE_7.0.0> sudo dnf versionlock add php

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.

netapp clustered data ontap MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy clustered-data-ontap || rpm -q clustered-data-ontap || clustered-data-ontap --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora ELN · fuse-sshfs · FIXED · 3.7.6-3.eln159 · FEDORA-2026-bcb7be7c5c · source

sudo dnf upgrade --advisory=FEDORA-2026-bcb7be7c5c

Fedora 46 · python-odata-query · FIXED · 0.10.1-1.fc46 · FEDORA-2026-eab44dc513 · source

sudo dnf upgrade --advisory=FEDORA-2026-eab44dc513

RHEL 5 · php · DEFERRED

RHEL 5 · php53 · DEFERRED

RHEL 6 · php · DEFERRED

RHEL 7 · php · DEFERRED

Amazon Linux 1 · see advisory · FIXED · ALAS-2017-812 · source

sudo yum update --advisory=ALAS-2017-812

Public exploits and detection

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

Write-up: bugs.php.net/bug.php?id=73832
Write-up: hackerone.com/reports/195950

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-2017-5340?

php: upgrade to 7.0.15, 7.1.1; clustered data ontap: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-5340 being exploited?

CVE-2017-5340 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-2017-5340 affect?

CVE-2017-5340 affects php, clustered data ontap. Severity is critical (CVSS 9.8). Zend/zend_hash.c in PHP before 7.0.15 and 7.1.x before 7.1.1 mishandles certain cases that require large array allocations, which allows remote attackers to execute arbitrary code or cause a denial of service (integer overflow, uninitialize

How urgent is CVE-2017-5340?

Priority 69/100. Critical severity; EPSS top 3%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

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References

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