CVE-2026-59947

Credential disclosure via unsanitized URL usernames

Published Jul 8, 2026 · Updated Jul 8, 2026

Information disclosure in Composer 1.0 through 2.2.28 and 2.3.0 through 2.10.1 allows local users to read credentials from debug output. AuthHelper logs HTTP-Basic usernames verbatim, while Url::sanitize and ProcessExecutor recognize only user:password URL forms and leave username-only tokens unmasked. Exposure requires a credential in the URL username slot, -vvv execution, and retained or shared output readable by another party; password-slot credentials are already masked.

CVSS severity4.7
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Composer 1.0 through 2.2.28 and 2.3.0 through 2.10.1 allows local users to read credentials from debug output. AuthHelper logs HTTP-Basic usernames verbatim, while Url::sanitize and ProcessExecutor recognize only user:password URL forms and leave username-only tokens unmasked. Exposure requires a credential in the URL username slot, -vvv execution, and retained or shared output readable by another party; password-slot credentials are already masked.

The record

CVE
CVE-2026-59947
Published
Jul 8, 2026
Updated
Jul 8, 2026
Vendor
Composer
Product
Composer
Classifications
CWE-532, T1552.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 8, 2026Record 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=>= 1.0, < 2.2.29
  2. Affected versionversion=>= 2.3.0, < 2.10.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Composer · Composerversion=>= 1.0, < 2.2.29; version=>= 2.3.0, < 2.10.2

Published CVSS scores

4.7GitHub, Inc.CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-532Insertion of Sensitive Information into Log File
T1552.001Credentials In Files

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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