CVE-2026-40261

HIGHPre-NVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 1.7%, top 25% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 2%CVSS: 8.8Exploit: Elevated riskExposed: 0

A fix is available — apply it.

Composer is a dependency manager for PHP. Versions 1.0 through 2.2.26 and 2.3 through 2.9.5 contain a command injection vulnerability in the Perforce::syncCodeBase() method, which appends the $sourceReference parameter to a shell command without proper escaping, and additionally in the Perforce::generateP4Command() method as in GHSA-wg36-wvj6-r67p / CVE-2026-40176, which interpolates user-supplied Perforce connection parameters (port, user, client) from the source url field without proper escaping. An attacker can inject arbitrary commands through crafted source reference or source url values containing shell metacharacters, even if Perforce is not installed. Unlike CVE-2026-40176, the source reference and url are provided as part of package metadata, meaning any compromised or malicious Composer repository can serve package metadata declaring perforce as a source type with malicious values. This vulnerability is exploitable when installing or updating dependencies from source, including the default behavior when installing dev-prefixed versions. This issue has been fixed in Composer 2.2.27 (2.2 LTS) and 2.9.6 (mainline). If developers are unable to immediately update, they can avoid installing dependencies from source by using --prefer-dist or the preferred-install: dist config setting, and only use trusted Composer repositories as a workaround.

CVSS v3
8.8
EG Score
8.8(medium)
EG Risk
40(Track)
EG Risk 40/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity88% × 45%
Exploitation2% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
2%
EPSS %ILE
75%
KEV
Not listed

Published

April 15, 2026

Last Modified

July 15, 2026

Advisory Details (2)

Auto-updated May 2, 2026
Patch available. Sources: github.
github Patch Available

Command injection via malicious Perforce source reference/url · Advisory · composer/composer · GitHub

https://github.com/composer/composer/security/advisories/GHSA-gqw4-4w2p-838q
generic

Release 2.9.6 · composer/composer · GitHub

https://github.com/composer/composer/releases/tag/2.9.6

Vendor Advisories for CVE-2026-40261(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatcomposer-main-2.9.7-1.hum12026-04-14redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
composer2.0.11-1 ... 2.9.8-1 (96 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
composer2.5.5-1, 2.5.5-1+deb12u1, 2.5.5-1+deb12u2, 2.5.5-1+deb12u32.5.5-1+deb12u4—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
composer2.8.8-1, 2.8.8-1+deb13u12.8.8-1+deb13u2—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
composer2.8.10-1 ... 2.9.5-1 (12 versions)2.9.7-1—
Packagist(1)
PackageVulnerable rangeFixed inDependents
composer/composer1.0.0 ... 2.2.9 (147 versions)2.2.27—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 49× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 177 total refreshes for this CVE.

  1. 2026-09-04 05:06 UTCEPSS rescore
  2. 2026-09-02 14:12 UTCEPSS rescore
  3. 2026-09-02 04:58 UTCOSV refresh
  4. 2026-09-01 13:53 UTCEPSS rescore
  5. 2026-09-01 04:39 UTCEPSS rescore
  6. 2026-08-30 19:17 UTCEPSS rescore
  7. 2026-08-30 01:22 UTCEPSS rescore
  8. 2026-08-28 21:41 UTCEPSS rescore
  9. 2026-08-27 14:25 UTCEPSS rescore
  10. 2026-08-26 14:46 UTCEPSS rescore
  11. 2026-08-25 13:49 UTCEPSS rescore
  12. 2026-08-23 00:19 UTCEPSS rescore
  13. 2026-08-21 23:49 UTCEPSS rescore
  14. 2026-08-20 22:55 UTCEPSS rescore
  15. 2026-08-19 17:03 UTCEPSS rescore
  16. 2026-08-18 13:48 UTCEPSS rescore
  17. 2026-08-17 13:47 UTCEPSS rescore
  18. 2026-08-16 14:56 UTCEPSS rescore
  19. 2026-08-16 06:37 UTCEG score recompute
  20. 2026-08-16 06:37 UTCVendor advisory
  21. 2026-08-16 02:14 UTCEPSS rescore
  22. 2026-08-15 01:30 UTCEPSS rescore
  23. 2026-08-14 16:06 UTCVendor advisory
  24. 2026-08-14 04:43 UTCEG score recompute
  25. 2026-08-14 04:43 UTCVendor advisory
Show 75 more
  1. 2026-08-13 22:00 UTCEPSS rescore
  2. 2026-08-13 08:56 UTCVendor advisory
  3. 2026-08-12 18:53 UTCEG score recompute
  4. 2026-08-12 18:53 UTCVendor advisory
  5. 2026-08-12 13:51 UTCEPSS rescore
  6. 2026-08-11 17:04 UTCEG score recompute
  7. 2026-08-11 17:04 UTCVendor advisory
  8. 2026-08-11 13:43 UTCEPSS rescore
  9. 2026-08-11 02:37 UTCEG score recompute
  10. 2026-08-11 02:37 UTCVendor advisory
  11. 2026-08-11 00:00 UTCEPSS rescore
  12. 2026-08-10 02:46 UTCVendor advisory
  13. 2026-08-09 15:23 UTCEG score recompute
  14. 2026-08-09 15:23 UTCVendor advisory
  15. 2026-08-09 13:46 UTCEPSS rescore
  16. 2026-08-09 03:59 UTCEG score recompute
  17. 2026-08-09 03:59 UTCVendor advisory
  18. 2026-08-08 16:37 UTCEPSS rescore
  19. 2026-08-08 00:48 UTCEG score recompute
  20. 2026-08-08 00:48 UTCVendor advisory
  21. 2026-08-07 13:25 UTCEG score recompute
  22. 2026-08-07 13:25 UTCVendor advisory
  23. 2026-08-06 13:46 UTCEPSS rescore
  24. 2026-08-06 12:06 UTCVendor advisory
  25. 2026-08-05 23:22 UTCEG score recompute
  26. 2026-08-05 23:22 UTCVendor advisory
  27. 2026-08-05 19:17 UTCEPSS rescore
  28. 2026-08-04 15:10 UTCEPSS rescore
  29. 2026-08-04 10:38 UTCEPSS rescore
  30. 2026-08-03 21:34 UTCEG score recompute
  31. 2026-08-03 21:34 UTCVendor advisory
  32. 2026-08-03 10:36 UTCEPSS rescore
  33. 2026-08-03 00:46 UTCVendor advisory
  34. 2026-08-02 13:13 UTCEG score recompute
  35. 2026-08-02 13:13 UTCVendor advisory
  36. 2026-08-02 02:27 UTCEPSS rescore
  37. 2026-08-01 04:16 UTCEPSS rescore
  38. 2026-07-30 16:28 UTCEPSS rescore
  39. 2026-07-30 01:30 UTCEPSS rescore
  40. 2026-07-27 14:13 UTCEPSS rescore
  41. 2026-07-26 14:54 UTCEPSS rescore
  42. 2026-07-26 14:54 UTCEPSS rescore
  43. 2026-07-25 14:18 UTCEPSS rescore
  44. 2026-07-25 14:18 UTCEPSS rescore
  45. 2026-07-24 14:17 UTCEPSS rescore
  46. 2026-07-24 14:17 UTCEPSS rescore
  47. 2026-07-23 14:18 UTCEPSS rescore
  48. 2026-07-23 14:18 UTCEPSS rescore
  49. 2026-07-23 03:11 UTCEG score recompute
  50. 2026-07-22 14:08 UTCEPSS rescore
  51. 2026-07-21 15:24 UTCEPSS rescore
  52. 2026-07-20 17:08 UTCEPSS rescore
  53. 2026-07-20 09:32 UTCOSV refresh
  54. 2026-07-19 14:31 UTCEPSS rescore
  55. 2026-07-19 02:29 UTCEPSS rescore
  56. 2026-07-18 10:04 UTCEPSS rescore
  57. 2026-07-16 17:03 UTCEPSS rescore
  58. 2026-07-15 16:57 UTCEPSS rescore
  59. 2026-07-15 16:57 UTCEPSS rescore
  60. 2026-07-15 02:00 UTCEPSS rescore
  61. 2026-07-13 22:30 UTCEPSS rescore
  62. 2026-07-13 06:13 UTCEPSS rescore
  63. 2026-07-13 06:13 UTCEPSS rescore
  64. 2026-07-12 05:46 UTCEPSS rescore
  65. 2026-07-11 08:27 UTCEPSS rescore
  66. 2026-07-09 19:10 UTCEPSS rescore
  67. 2026-07-08 15:15 UTCEPSS rescore
  68. 2026-07-07 13:46 UTCEPSS rescore
  69. 2026-07-06 16:27 UTCEPSS rescore
  70. 2026-07-06 16:27 UTCEPSS rescore
  71. 2026-07-06 02:23 UTCEPSS rescore
  72. 2026-07-06 02:23 UTCEPSS rescore
  73. 2026-07-05 02:30 UTCEPSS rescore
  74. 2026-07-04 06:31 UTCEPSS rescore
  75. 2026-07-01 15:06 UTCEPSS rescore

Publicly available exploits

(1 reference)

Working exploit code is in the public domain (1 GitHub PoC). Defenders should treat patch urgency accordingly — public PoCs typically lead to mass-exploitation within 24-72 hours.

  • GitHub PoCterminat0r7031/composer-CVE-2026-40261-CVE-2026-40176-PoC
    First seen Apr 16, 2026
    Open source ↗

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-40261?
CVE-2026-40261 is a high vulnerability published on April 15, 2026. Composer is a dependency manager for PHP. Versions 1.0 through 2.2.26 and 2.3 through 2.9.5 contain a command injection vulnerability in the Perforce::syncCodeBase() method, which appends the $sourceReference parameter to a shell command without proper escaping, and additionally in the…
When was CVE-2026-40261 disclosed?
CVE-2026-40261 was first published in the National Vulnerability Database on April 15, 2026, with the most recent update on July 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40261 actively exploited?
CVE-2026-40261 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2% probability of exploitation in the next 30 days, which ranks it in the top 24.5% of all scored CVEs.
What is the CVSS score of CVE-2026-40261?
CVE-2026-40261 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2026-40261?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40261, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-40261

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