CVE-2018-1000518

mediumpriority · track · 31EPSS 0.018 · 79 %ileEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

1.83% (79th) EPSS

CVSS 5 · medium

Is it mine?

4 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · osv · nvd

EPSS · scored 2026-10-27

aaugustin websockets version 4 contains a CWE-409: Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in Servers and clients, unless configured with compression=None that can result in Denial of Service by memory exhaustion. This attack appear to be exploitable via Sending a specially crafted frame on an established connection. This vulnerability appears to have been fixed in 5.

cvss

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5–7.5

v2.05mediumAV:N/AC:L/Au:N/C:N/I:N/A:Pprimary · NVD / NIST USexploitability 10 · impact 2.9

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 3.6

v3.07.5highCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · OSV

v3.16.9mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-400USprimaryCWE-400US

affected products (4)

Products and version ranges known to be affected.

n/a n/a≤ n/aenisa_euvdEU
websockets project websockets= 4.0nvdUScpe:2.3:a:websockets_project:websockets:*:*:*:*:*:*:*:*
PyPI websockets< 5.0osvUSpkg:pypi/websockets
PyPI websockets4.0 → 5.0osvUSpkg:pypi/websockets

advisories (2)

Vendor and ecosystem advisories describing this.

GHSA-6g87-ff9q-v847websockets is vulnerable to denial of service by memory exhaustion2018-09-17ghsa · osvUS
The Python websockets library version 4 contains a CWE-409: Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in Servers and clients, unless configured with compression=None that can result in Denial of Service by memory exhaustion. This attack appears to be exploitable via sending a specially crafted frame on an established connection. This vulnerability appears to have been fixed in version 5.0
PYSEC-2018-792018-06-26vendor · osvUS
aaugustin websockets version 4 contains a CWE-409: Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in Servers and clients, unless configured with compression=None that can result in Denial of Service by memory exhaustion. This attack appear to be exploitable via Sending a specially crafted frame on an established connection. This vulnerability appears to have been fixed in 5.

also known as (6)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd osv nvd NVD CVE.org MITRE

published 2018-06-26modified 2026-06-17

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+9611 more

references (4)

External citations — patches, advisories, analysis.

scry

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