CVE-2026-6104

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 0.5%, top 62% 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
9.1
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.1Exploit: NoneExposed: 0

A fix is available — apply it.

In PHP versions 8.4.* before 8.4.21 and 8.5.* before 8.5.6, when an encoding name containing an embedded NUL byte is passed to mb_convert_encoding() or related mbstring functions, the code incorrectly assumes that when strncasecmp() returns 0 it means the strings have the same length. This can lead to out-of-bounds read of global memory, potentially causing a crash or information disclosure or crash. Affected functions include mb_convert_encoding(), mb_detect_encoding(), mb_convert_variables(), and mb_detect_order(), as well as the mbstring.detect_order and mbstring.http_output INI settings.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
56(Track)
EG Risk 56/100SSVC: 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
Severity91% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
37.9%
KEV
Not listed

Published

May 10, 2026

Last Modified

July 15, 2026

Advisory Details (1)

Auto-updated May 10, 2026
Patch available. Sources: github.
github Patch Available

Global buffer over-read in mb_convert_encoding() with attacker-supplied encoding · Advisory · php/php-src · GitHub

https://github.com/php/php-src/security/advisories/GHSA-74r9-qxhc-fx53

Vendor Advisories for CVE-2026-6104(1)

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

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntuphp8.1-zip (8.1.2-1ubuntu2.24) @ jammy2026-06-28ubuntu
redhatphp8.4-0:8.4.21-1.el10_22026-06-02redhat

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.

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 10× in last 7d / 51× 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 184 total refreshes for this CVE.

  1. 2026-07-23 03:21 UTCEG score recompute
  2. 2026-07-22 14:08 UTCEPSS rescore
  3. 2026-07-22 14:08 UTCEPSS rescore
  4. 2026-07-21 15:25 UTCEPSS rescore
  5. 2026-07-21 15:25 UTCEPSS rescore
  6. 2026-07-20 17:08 UTCEPSS rescore
  7. 2026-07-19 14:31 UTCEPSS rescore
  8. 2026-07-19 02:29 UTCEPSS rescore
  9. 2026-07-18 10:04 UTCEPSS rescore
  10. 2026-07-16 17:03 UTCEPSS rescore
  11. 2026-07-15 16:57 UTCEPSS rescore
  12. 2026-07-15 02:00 UTCEPSS rescore
  13. 2026-07-15 02:00 UTCEPSS rescore
  14. 2026-07-15 01:23 UTCNVD updateCVSS v3 → 9.1 · severity → CRITICAL
  15. 2026-07-15 00:50 UTCMITRE cvelistV5CVSS v3 → 8.2 · severity → HIGH
  16. 2026-07-13 22:31 UTCEPSS rescore
  17. 2026-07-13 06:13 UTCEPSS rescore
  18. 2026-07-13 06:13 UTCEPSS rescore
  19. 2026-07-12 05:46 UTCEPSS rescore
  20. 2026-07-11 08:27 UTCEPSS rescore
  21. 2026-07-11 08:27 UTCEPSS rescore
  22. 2026-07-09 19:10 UTCEPSS rescore
  23. 2026-07-09 19:10 UTCEPSS rescore
  24. 2026-07-08 15:16 UTCEPSS rescore
  25. 2026-07-08 15:16 UTCEPSS rescore
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  1. 2026-07-07 13:46 UTCEPSS rescore
  2. 2026-07-07 13:46 UTCEPSS rescore
  3. 2026-07-06 16:27 UTCEPSS rescore
  4. 2026-07-06 16:27 UTCEPSS rescore
  5. 2026-07-06 02:23 UTCEPSS rescore
  6. 2026-07-06 02:23 UTCEPSS rescore
  7. 2026-07-05 02:31 UTCEPSS rescore
  8. 2026-07-05 02:30 UTCEPSS rescore
  9. 2026-07-04 06:31 UTCEPSS rescore
  10. 2026-07-04 06:31 UTCEPSS rescore
  11. 2026-07-01 15:07 UTCEPSS rescore
  12. 2026-06-30 23:22 UTCEPSS rescore
  13. 2026-06-29 14:06 UTCEPSS rescore
  14. 2026-06-28 14:07 UTCEPSS rescore
  15. 2026-06-28 08:54 UTCVendor advisory
  16. 2026-06-28 04:56 UTCEPSS rescore
  17. 2026-06-28 03:37 UTCVendor advisory
  18. 2026-06-27 14:08 UTCVendor advisory
  19. 2026-06-27 10:23 UTCVendor advisory
  20. 2026-06-27 03:08 UTCEPSS rescore
  21. 2026-06-26 21:10 UTCVendor advisory
  22. 2026-06-26 05:31 UTCVendor advisory
  23. 2026-06-25 13:50 UTCEPSS rescore
  24. 2026-06-24 14:05 UTCEPSS rescore
  25. 2026-06-23 21:33 UTCEPSS rescore
  26. 2026-06-23 21:33 UTCEPSS rescore
  27. 2026-06-22 14:25 UTCEPSS rescore
  28. 2026-06-22 14:25 UTCEPSS rescore
  29. 2026-06-21 14:56 UTCEPSS rescore
  30. 2026-06-21 14:56 UTCEPSS rescore
  31. 2026-06-21 01:59 UTCEPSS rescore
  32. 2026-06-21 01:59 UTCEPSS rescore
  33. 2026-06-19 19:26 UTCEPSS rescore
  34. 2026-06-19 19:26 UTCEPSS rescore
  35. 2026-06-18 17:52 UTCEPSS rescore
  36. 2026-06-18 17:52 UTCEPSS rescore
  37. 2026-06-17 17:53 UTCEPSS rescore
  38. 2026-06-17 05:39 UTCVendor advisory
  39. 2026-06-17 01:10 UTCVendor advisory
  40. 2026-06-16 17:53 UTCEPSS rescore
  41. 2026-06-16 07:45 UTCVendor advisory
  42. 2026-06-15 17:49 UTCEPSS rescore
  43. 2026-06-15 17:49 UTCEPSS rescore
  44. 2026-06-15 05:45 UTCVendor advisory
  45. 2026-06-15 02:04 UTCVendor advisory
  46. 2026-06-14 23:18 UTCEPSS rescore
  47. 2026-06-14 22:22 UTCVendor advisory
  48. 2026-06-14 18:30 UTCVendor advisory
  49. 2026-06-14 14:37 UTCVendor advisory
  50. 2026-06-14 10:35 UTCVendor advisory
  51. 2026-06-14 06:43 UTCVendor advisory
  52. 2026-06-14 02:15 UTCVendor advisory
  53. 2026-06-13 23:00 UTCEPSS rescore
  54. 2026-06-13 08:56 UTCVendor advisory
  55. 2026-06-13 02:26 UTCVendor advisory
  56. 2026-06-12 23:12 UTCEPSS rescore
  57. 2026-06-12 23:12 UTCEPSS rescore
  58. 2026-06-12 22:43 UTCVendor advisory
  59. 2026-06-12 18:28 UTCVendor advisory
  60. 2026-06-12 11:41 UTCVendor advisory
  61. 2026-06-12 08:00 UTCVendor advisory
  62. 2026-06-12 04:17 UTCVendor advisory
  63. 2026-06-12 00:29 UTCVendor advisory
  64. 2026-06-11 20:48 UTCVendor advisory
  65. 2026-06-11 17:07 UTCVendor advisory
  66. 2026-06-11 14:00 UTCEPSS rescore
  67. 2026-06-11 11:44 UTCVendor advisory
  68. 2026-06-11 08:02 UTCVendor advisory
  69. 2026-06-11 04:18 UTCVendor advisory
  70. 2026-06-11 00:36 UTCVendor advisory
  71. 2026-06-10 22:19 UTCEPSS rescore
  72. 2026-06-10 20:55 UTCVendor advisory
  73. 2026-06-10 17:08 UTCVendor advisory
  74. 2026-06-10 13:25 UTCVendor advisory
  75. 2026-06-10 13:22 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-6104?
CVE-2026-6104 is a critical vulnerability published on May 10, 2026. In PHP versions 8.4. before 8.4.21 and 8.5. before 8.5.6, when an encoding name containing an embedded NUL byte is passed to mbconvertencoding() or related mbstring functions, the code incorrectly assumes that when strncasecmp() returns 0 it means the strings have the same length. This can lead to…
When was CVE-2026-6104 disclosed?
CVE-2026-6104 was first published in the National Vulnerability Database on May 10, 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-2026-6104 actively exploited?
CVE-2026-6104 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 37.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-6104?
CVE-2026-6104 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-6104?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-6104, 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.

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