CVE-2026-59948

Summary

A maliciously crafted package, published on an untrusted third party repository other than Packagist.org or Private Packagist, can cause Composer to write files outside the vendor/ directory and outside your project, with attacker-controlled content, during a normal install or update through using an invalid package name, which was not correctly validated by Composer.

This is an arbitrary file write that can be used to execute code outside the Composer project's context in which you expected the package code to execute (for example by writing shell startup files, SSH authorized_keys, or a cron entry). It is a supply-chain issue: it requires a malicious or compromised package to be present in the dependency graph, it is not otherwise remotely exploitable against a machine.

The fix makes Composer validate every package produced by dependency resolution before anything is written to composer.lock or installed, and abort with a security error if a package name is not a valid vendor/package name.

Am I affected?

You may be affected if you install packages from an untrusted third party repository, which does not sufficiently validate package names. Packagist.org and Private Packagist are safe, as they validate package names correctly.

Patched versions

Fixed in 2.2.29 and 2.10.2. Composer 1.x is also affected and you should move to a safe 2.x release.

Workarounds

Do not use untrusted package repositories. If you have to, mirror them through an internal repository like Private Packagist.

Composer is a dependency Manager for the PHP language. Prior to 2.2.29 and 2.10.2, a maliciously crafted package from an untrusted repository other than Packagist.org or Private Packagist can cause Composer to write attacker-controlled files outside the vendor directory and outside the project during install or update by using an invalid package name that is not correctly validated before dependency-resolution results are written or installed. This issue is fixed in versions 2.2.29 and 2.10.2.

Composer is a dependency Manager for the PHP language. Prior to 2.2.29 and 2.10.2, a maliciously crafted package from an untrusted repository other than Packagist.org or Private Packagist can cause Composer to write attacker-controlled files outside the vendor directory and outside the project during install or update by using an invalid package name that is not correctly validated before dependency-resolution results are written or installed. This issue is fixed in versions 2.2.29 and 2.10.2.

These are all security issues fixed in the php-composer2-2.10.2-1.1 package on the GA media of openSUSE Tumbleweed.

This update for php-composer2 fixes the following issues:

• CVE-2026-45793: Github Actions issued GITHUB_TOKEN disclosure in GitHub Actions logs (bsc#1271504).
• CVE-2026-59946: path traversal in package bin field lets dependencies chmod arbitrary host files (bsc#1271151).
• CVE-2026-59947: URL-embedded HTTP-Basic username leaks to verbose logs (bsc#1271129).
• CVE-2026-59948: arbitrary file write outside vendordirectory via malicious transitive package name (bsc#1271122).

Changes for php-composer2:

• fix byte-swapped signature on s390x can cause broken or unsupported signature (bsc#1271729).

This update for php-composer2 fixes the following issues:

• CVE-2026-45793: Github Actions issued GITHUB_TOKEN disclosure in GitHub Actions logs (bsc#1271504).
• CVE-2026-59946: path traversal in package bin field lets dependencies chmod arbitrary host files (bsc#1271151).
• CVE-2026-59947: URL-embedded HTTP-Basic username leaks to verbose logs (bsc#1271129).
• CVE-2026-59948: arbitrary file write outside vendordirectory via malicious transitive package name (bsc#1271122).

Changes for php-composer2:

• fix byte-swapped signature on s390x can cause broken or unsupported signature (bsc#1271729).

This update for php-composer2 fixes the following issues:

• CVE-2026-45793: Github Actions issued GITHUB_TOKEN disclosure in GitHub Actions logs (bsc#1271504).
• CVE-2026-59946: path traversal in package bin field lets dependencies chmod arbitrary host files (bsc#1271151).
• CVE-2026-59947: URL-embedded HTTP-Basic username leaks to verbose logs (bsc#1271129).
• CVE-2026-59948: arbitrary file write outside vendordirectory via malicious transitive package name (bsc#1271122).

Changes for php-composer2:

• fix byte-swapped signature on s390x can cause broken or unsupported signature (bsc#1271729).

This update for php-composer2 fixes the following issues:

• CVE-2026-45793: Github Actions issued GITHUB_TOKEN disclosure in GitHub Actions logs (bsc#1271504).
• CVE-2026-59946: path traversal in package bin field lets dependencies chmod arbitrary host files (bsc#1271151).
• CVE-2026-59947: URL-embedded HTTP-Basic username leaks to verbose logs (bsc#1271129).
• CVE-2026-59948: arbitrary file write outside vendordirectory via malicious transitive package name (bsc#1271122).

This update for php-composer2 fixes the following issues:

• CVE-2026-45793: GitHub OAuth tokens failing regex validation can cause credential disclosure (bsc#1271504).
• CVE-2026-59944: path traversal and link following issue can make files world readable and executable (bsc#1279898).
• CVE-2026-59946: package bin entries with path segments can cause unintended host file permission modifications (bsc#1271152).
• CVE-2026-59947: unsanitized URL credential handling in debug output within Composer can allow sensitive token disclosure (bsc#1271130).
• CVE-2026-59948: missing package name validation during dependency resolution in Composer can allow path traversal (bsc#1271123).
• CVE-2026-84361: arbitrary code execution via malicious Perforce source URL (bsc#1278257).

Changes for php-composer2:

• version update to 2.2.30:

• Fixed command injection via malicious Perforce url (GHSA-rvx4-ffvw-m9q3)
• Sanitize URL-embedded usernames/token in a few more places (#13045)
• Fixed matching of gitlab URLs to avoid possible credential leak to the wrong domain (#13042)

• fix a regression on s390x due last change (bsc#1271729).

• version update to 2.2.29:

• Validate package names (GHSA-499r-g7pc-vmp9)
• Validate package bin paths against path traversal (GHSA-gjfg-22fp-rrxx)
• Sanitize URL-embedded usernames/token in verbose output (GHSA-g6xq-892h-64w3)
• Only follow HTTP redirects from HTTP responses (#12948)
• Prevent phar metadata unserialization on unsafe PHP versions (#12946)
• Sanitize JSON parse errors in http responses to avoid leaking response body data (#12959)
• Fixed GitHub token validation to be even more relaxed (#12856)

• version update to 2.2.28.

This update for php-composer2 fixes the following issues:

• CVE-2026-59946: package bin entries with path segments can cause unintended host file permission modifications (bsc#1271152).
• CVE-2026-59947: unsanitized URL credential handling in debug output within Composer can allow sensitive token disclosure (bsc#1271130).
• CVE-2026-59948: missing package name validation during dependency resolution in Composer can allow path traversal (bsc#1271123).