CVE-2026-72678: Elasticsearch does not validate a size value taken from a user-supplied input before that value is used to res

Routine

MEDIUM 6.5UPGRADE

CVE-2026-72678 is a medium-severity flaw (CVSS 6.5) affecting elasticsearch. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Elasticsearch does not validate a size value taken from a user-supplied input before that value is used to reserve memory for an internal data structure. An authenticated user holding only read privileges can submit a single small crafted request to a product API endpoint that causes the node to attempt an excessively large allocation. The resulting memory exhaustion raises a fatal error that terminates the Elasticsearch node process, causing a d

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.5% (top 59%)
CISA exploited list	No
Weakness	CWE-789
Published	2026-08-13
Last modified	2026-09-01

Publisher (CNA): Elastic · Vendor: elastic

Last updated 2026-09-01 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-13 20:17 UTCPublished CVE record published
2026-09-01 15:28 UTCUpdated Record last modified

elastic elasticsearch UPGRADE

Affected: >= 8.19.0 and < 8.19.20 · >= 9.4.0 and < 9.4.5 · >= 9.5.0 and < 9.5.1

Fixed in: 8.19.20, 9.4.5, 9.5.1

Safe to downgrade to: a release before 8.19.0

1. Check installed version

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

2. UPGRADE to 8.19.20 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade elasticsearch

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 8.19.0 (Debian / Ubuntu)

apt-cache madison elasticsearch sudo apt install elasticsearch=<VERSION_BEFORE_8.19.0> sudo apt-mark hold elasticsearch

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

dnf --showduplicates list elasticsearch sudo dnf downgrade elasticsearch-<VERSION_BEFORE_8.19.0> sudo dnf versionlock add elasticsearch

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-2026-72678?

elasticsearch: upgrade to 8.19.20, 9.4.5, 9.5.1. Exact commands for each OS are on this page.

Is CVE-2026-72678 being exploited?

CVE-2026-72678 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-2026-72678 affect?

CVE-2026-72678 affects elasticsearch. Severity is medium (CVSS 6.5). Elasticsearch does not validate a size value taken from a user-supplied input before that value is used to reserve memory for an internal data structure. An authenticated user holding only read privileges can submit a single small crafted r

How urgent is CVE-2026-72678?

Priority 33/100. No elevated risk signals yet.

Software pages

Elasticsearch vulnerabilities

Related CVEs

CVE-2026-56148 MEDIUM 6.5 UPGRADE Uncontrolled Recursion (CWE-674) in Elasticsearch can lead to a denial of service via Excessive Allocation (CA
CVE-2026-49090 MEDIUM 6.5 UPGRADE Uncontrolled Resource Consumption (CWE-400) in Elasticsearch can lead to a denial of service via Excessive All
CVE-2026-56149 MEDIUM 4.9 UPGRADE Allocation of Resources Without Limits or Throttling (CWE-770) in Elasticsearch can lead to a denial of servic
CVE-2026-56145 MEDIUM 6.5 UPGRADE Uncontrolled Resource Consumption (CWE-400) in Elasticsearch can lead to denial of service via Excessive Alloc
CVE-2026-63136 MEDIUM 6.5 UPGRADE Uncontrolled Resource Consumption (CWE-400) in Elasticsearch can lead to denial of service via Excessive Alloc

References

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