CVE-2026-14587: Neo4j's Bolt modern handshake decoder treats an overlong capability bit mask the same way it treats a truncate

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HIGH 7.5REMOTEUPGRADE

CVE-2026-14587 is a high-severity flaw (CVSS 7.5) affecting neo4j. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Neo4j's Bolt modern handshake decoder treats an overlong capability bit mask the same way it treats a truncated bit mask. When an unauthenticated client sends a selected protocol version followed by 32 continuation bytes in the capability mask, the decoder resets the reader index and waits for more bytes instead of rejecting the protocol message and closing the channel. Because the same unread bytes remain at the front of the decoder buffer, a

Why this priority

High severity
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	0.5% (top 55%)
CISA exploited list	No
Weakness	CWE-130
Published	2026-08-05
Last modified	2026-08-28

Publisher (CNA): Neo4j · Vendor: neo4j

Last updated 2026-08-28 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-05 17:16 UTCPublished CVE record published
2026-08-28 16:08 UTCUpdated Record last modified

neo4j neo4j UPGRADE

Affected: >= 5.0.0 and < 5.26.29 · >= 2025.01.0 and < 2026.07.0

Fixed in: 5.26.29, 2026.07.0

Safe to downgrade to: a release before 5.0.0

1. Check installed version

apt-cache policy neo4j || rpm -q neo4j || neo4j --version

2. UPGRADE to 5.26.29 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade neo4j

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade neo4j

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 5.0.0 (Debian / Ubuntu)

apt-cache madison neo4j sudo apt install neo4j=<VERSION_BEFORE_5.0.0> sudo apt-mark hold neo4j

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

dnf --showduplicates list neo4j sudo dnf downgrade neo4j-<VERSION_BEFORE_5.0.0> sudo dnf versionlock add neo4j

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-2026-14587?

neo4j: upgrade to 5.26.29, 2026.07.0. Exact commands for each OS are on this page.

Is CVE-2026-14587 being exploited?

CVE-2026-14587 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-2026-14587 affect?

CVE-2026-14587 affects neo4j. Severity is high (CVSS 7.5). Neo4j's Bolt modern handshake decoder treats an overlong capability bit mask the same way it treats a truncated bit mask. When an unauthenticated client sends a selected protocol version followed by 32 continuation bytes in the capability m

How urgent is CVE-2026-14587?

Priority 43/100. High severity; Remotely exploitable, no login, no user action

Software pages

Neo4j vulnerabilities

References

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