CVE-2019-15608Network attack vector

Cache poisoning via stale integrity hash

Published Mar 15, 2020 · Updated Aug 5, 2024

TOCTOU in Yarn package integrity validation before 1.19.0 allows remote attackers to poison the dependency cache via crafted package metadata. Yarn computes a package hash before caching but does not recompute it when reading cached content, allowing a malicious artifact to satisfy later integrity checks. Exploitation requires control of package metadata or delivery; installs can then consume attacker-supplied code, compromising dependency integrity.

CVSS severity5.9
Medium
EPSS probability1.83%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

TOCTOU in Yarn package integrity validation before 1.19.0 allows remote attackers to poison the dependency cache via crafted package metadata. Yarn computes a package hash before caching but does not recompute it when reading cached content, allowing a malicious artifact to satisfy later integrity checks. Exploitation requires control of package metadata or delivery; installs can then consume attacker-supplied code, compromising dependency integrity.

The record

CVE
CVE-2019-15608
Published
Mar 15, 2020
Updated
Aug 5, 2024
Vendor
Yarn
Product
Yarn
Classifications
CWE-367, CWE-840, T1195.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 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=Fixed in 1.19.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Yarn · Yarnversion=Fixed in 1.19.0

Published CVSS scores

5.9NISTCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
6.8NISTAV:N/AC:M/Au:N/C:N/I:P/A: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.

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
CWE-840Business Logic Errors
T1195.002Compromise Software Supply Chain

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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