CVE-2026-6409

HIGHNVD 7.17.1—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.1 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 72% 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, nvd
Trending — 3 sources updated this week
7.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.1Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

A Denial of Service (DoS) vulnerability exists in the Protobuf PHP library during the parsing of untrusted input. Maliciously structured messages—specifically those containing negative varints or deep recursion—can be used to crash the application, impacting service availability.

CVSS v3
7.1
EG Score
7.1(medium)
EG Risk
32(Track)
EG Risk 32/100SSVC: 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
Severity71% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
28.5%
KEV
Not listed

Published

April 16, 2026

Last Modified

April 17, 2026

Advisory Details (1)

Auto-updated Jun 14, 2026
Patch available. Sources: github.
github Patch Available

A potential Denial of Service issue in protobuf-php · Advisory · protocolbuffers/protobuf · GitHub

https://github.com/protocolbuffers/protobuf/security/advisories/GHSA-p2gh-cfq4-4wjc

Vendor Advisories for CVE-2026-6409(1)

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

Affected Packages

(1 across 1 ecosystem)
Packagist(1)
PackageVulnerable rangeFixed inDependents
google/protobufv3.1.0-alpha-1 ... v4.33.5 (202 versions)4.33.6—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 44× 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 107 total refreshes for this CVE.

  1. 2026-07-23 14:18 UTCEPSS rescore
  2. 2026-07-23 14:18 UTCEPSS rescore
  3. 2026-07-23 03:22 UTCEG score recompute
  4. 2026-07-22 14:08 UTCEPSS rescore
  5. 2026-07-22 14:08 UTCEPSS rescore
  6. 2026-07-21 15:25 UTCEPSS rescore
  7. 2026-07-21 15:25 UTCEPSS rescore
  8. 2026-07-20 17:08 UTCEPSS rescore
  9. 2026-07-20 08:32 UTCOSV refresh
  10. 2026-07-19 14:31 UTCEPSS rescore
  11. 2026-07-19 02:29 UTCEPSS rescore
  12. 2026-07-18 10:04 UTCEPSS rescore
  13. 2026-07-16 17:03 UTCEPSS rescore
  14. 2026-07-15 16:57 UTCEPSS rescore
  15. 2026-07-15 02:00 UTCEPSS rescore
  16. 2026-07-15 02:00 UTCEPSS rescore
  17. 2026-07-13 22:31 UTCEPSS rescore
  18. 2026-07-13 06:13 UTCEPSS rescore
  19. 2026-07-13 06:13 UTCEPSS rescore
  20. 2026-07-12 05:46 UTCEPSS rescore
  21. 2026-07-11 08:27 UTCEPSS rescore
  22. 2026-07-11 08:27 UTCEPSS rescore
  23. 2026-07-09 19:10 UTCEPSS rescore
  24. 2026-07-09 19:10 UTCEPSS rescore
  25. 2026-07-08 15:16 UTCEPSS rescore
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  1. 2026-07-08 15:16 UTCEPSS rescore
  2. 2026-07-07 13:46 UTCEPSS rescore
  3. 2026-07-07 13:46 UTCEPSS rescore
  4. 2026-07-06 02:23 UTCEPSS rescore
  5. 2026-07-06 02:23 UTCEPSS rescore
  6. 2026-07-05 02:31 UTCEPSS rescore
  7. 2026-07-05 02:30 UTCEPSS rescore
  8. 2026-07-04 06:31 UTCEPSS rescore
  9. 2026-07-04 06:31 UTCEPSS rescore
  10. 2026-07-01 15:07 UTCEPSS rescore
  11. 2026-06-30 23:22 UTCEPSS rescore
  12. 2026-06-29 14:06 UTCEPSS rescore
  13. 2026-06-28 14:07 UTCEPSS rescore
  14. 2026-06-28 04:56 UTCEPSS rescore
  15. 2026-06-27 03:08 UTCEPSS rescore
  16. 2026-06-25 13:50 UTCEPSS rescore
  17. 2026-06-24 14:05 UTCEPSS rescore
  18. 2026-06-23 21:33 UTCEPSS rescore
  19. 2026-06-23 21:33 UTCEPSS rescore
  20. 2026-06-22 14:25 UTCEPSS rescore
  21. 2026-06-22 14:25 UTCEPSS rescore
  22. 2026-06-21 14:56 UTCEPSS rescore
  23. 2026-06-21 14:56 UTCEPSS rescore
  24. 2026-06-21 01:59 UTCEPSS rescore
  25. 2026-06-21 01:59 UTCEPSS rescore
  26. 2026-06-19 19:26 UTCEPSS rescore
  27. 2026-06-19 19:26 UTCEPSS rescore
  28. 2026-06-18 17:52 UTCEPSS rescore
  29. 2026-06-18 17:52 UTCEPSS rescore
  30. 2026-06-17 17:53 UTCEPSS rescore
  31. 2026-06-16 17:53 UTCEPSS rescore
  32. 2026-06-15 17:49 UTCEPSS rescore
  33. 2026-06-15 17:49 UTCEPSS rescore
  34. 2026-06-14 23:18 UTCEPSS rescore
  35. 2026-06-14 19:52 UTCVendor advisory
  36. 2026-06-13 23:00 UTCEPSS rescore
  37. 2026-06-12 23:12 UTCEPSS rescore
  38. 2026-06-12 23:12 UTCEPSS rescore
  39. 2026-06-11 18:53 UTCVendor advisory
  40. 2026-06-11 14:00 UTCEPSS rescore
  41. 2026-06-10 22:29 UTCVendor advisory
  42. 2026-06-10 22:19 UTCEPSS rescore
  43. 2026-06-10 13:22 UTCEPSS rescore
  44. 2026-06-10 11:24 UTCVendor advisory
  45. 2026-06-10 00:19 UTCVendor advisory
  46. 2026-06-09 10:03 UTCVendor advisory
  47. 2026-06-08 14:23 UTCVendor advisory
  48. 2026-06-08 14:17 UTCEPSS rescore
  49. 2026-06-08 03:12 UTCVendor advisory
  50. 2026-06-07 16:06 UTCVendor advisory
  51. 2026-06-07 15:25 UTCEPSS rescore
  52. 2026-06-07 05:01 UTCVendor advisory
  53. 2026-06-06 13:47 UTCEPSS rescore
  54. 2026-06-06 08:56 UTCVendor advisory
  55. 2026-06-05 22:47 UTCEPSS rescore
  56. 2026-06-05 12:16 UTCVendor advisory
  57. 2026-06-05 06:10 UTCEPSS rescore
  58. 2026-06-04 23:04 UTCVendor advisory
  59. 2026-06-04 13:12 UTCEPSS rescore
  60. 2026-06-03 18:16 UTCVendor advisory
  61. 2026-06-02 20:13 UTCEPSS rescore
  62. 2026-06-02 14:05 UTCVendor advisory
  63. 2026-06-01 18:06 UTCEG score recompute▲ 7.10
  64. 2026-06-01 18:06 UTCVendor advisory
  65. 2026-06-01 13:52 UTCEPSS rescore
  66. 2026-06-01 13:52 UTCEPSS rescore
  67. 2026-05-31 22:30 UTCEPSS rescore
  68. 2026-05-31 22:30 UTCEPSS rescore
  69. 2026-05-31 00:16 UTCEPSS rescore
  70. 2026-05-31 00:16 UTCEPSS rescore
  71. 2026-05-29 13:44 UTCEPSS rescore
  72. 2026-05-29 13:44 UTCEPSS rescore
  73. 2026-05-28 13:44 UTCEPSS rescore
  74. 2026-05-28 13:44 UTCEPSS rescore
  75. 2026-05-27 13:40 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-6409?
CVE-2026-6409 is a high vulnerability published on April 16, 2026. A Denial of Service (DoS) vulnerability exists in the Protobuf PHP library during the parsing of untrusted input. Maliciously structured messages—specifically those containing negative varints or deep recursion—can be used to crash the application, impacting service availability.
When was CVE-2026-6409 disclosed?
CVE-2026-6409 was first published in the National Vulnerability Database on April 16, 2026, with the most recent update on April 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-6409 actively exploited?
CVE-2026-6409 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 28.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-6409?
CVE-2026-6409 has a CVSS v3 base score of 7.1 (NVD).
How do I remediate CVE-2026-6409?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-6409, 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

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