[UPDATE] [high] Composer: Multiple vulnerabilities allow code execution

highCVE-2026-40176 CVE-2026-40261

An attacker can exploit multiple vulnerabilities in Composer to execute arbitrary program code.

CSIRTS triage

vendor: Composer product: Composer Remote code execution

What: Multiple vulnerabilities allow arbitrary code execution.
Who is affected: Attackers targeting installations of Composer.
Urgency: Remediation is high urgency due to the potential for severe impacts.
Action: Update to the latest version of Composer.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: CERT-Bund (BSI) Security Advisories (DE · national-cert · site)
Severity: high
Published: 2026-07-20
Exploitation: Not in CISA KEV at last sync
Language: Machine-translated to English — verify against the original

Original advisory: https://wid.cert-bund.de/portal/wid/securityadvisory?name=WID-SEC-2026-1128

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Moderate exploitation riskCVE-2026-401761.1% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 61% of all scored CVEs.
Moderate exploitation riskCVE-2026-402611.7% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 75% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-40176	coverage & exploitation status	NVD · CVE.org
CVE-2026-40261	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for Composer

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

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mediumGHSA-w6w4-rjh9-9r58: c3p0 can, in combination with other libraries, compose to a "sink" for deserialization ga…ghsa · 2026-07-23
highCVE-2026-65896: Grav API Plugin (Composer package getgrav/grav-plugin-api) before 1.0.10 fails to properly val…nvd · 2026-07-23
mediumGHSA-8mv7-9c27-98vc: Astro: composable `astro/hono` pipeline bypasses `security.checkOrigin` when `middleware(…ghsa · 2026-07-20
mediumGHSA-gjfg-22fp-rrxx: Composer: Path traversal in package bin field lets dependencies chmod arbitrary host file…ghsa · 2026-07-20