CVE-2018-16848Network attack vector

Service interruption via recursive YAML anchor expansion

Published Jun 15, 2020 · Updated Aug 5, 2024

Resource exhaustion in OpenStack Mistral 7.0.3 and earlier allows remote authenticated users to interrupt service via crafted workflow YAML. The workflow parser passes attacker-controlled definitions to PyYAML loaders that recursively expand nested anchors, causing exponential memory consumption. A user able to submit workflow definitions through the REST API can exhaust server resources and interrupt Mistral availability.

CVSS severity6.5
Medium
EPSS probability1.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in OpenStack Mistral 7.0.3 and earlier allows remote authenticated users to interrupt service via crafted workflow YAML. The workflow parser passes attacker-controlled definitions to PyYAML loaders that recursively expand nested anchors, causing exponential memory consumption. A user able to submit workflow definitions through the REST API can exhaust server resources and interrupt Mistral availability.

The record

CVE
CVE-2018-16848
Published
Jun 15, 2020
Updated
Aug 5, 2024
Vendor
OpenStack
Product
Mistral
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 15, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=up to and including 7.0.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

OpenStack · Mistralversion=up to and including 7.0.3

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0NIST NVDAV:N/AC:L/Au:S/C:N/I:N/A:P
7.1GitHub Advisory DatabaseCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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