CVE-2026-34827

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 61% 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
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 7.5Exploit: None knownExposed: 0

A fix is available — apply it.

Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21, and 3.2.0 to before 3.2.6, Rack::Multipart::Parser#handle_mime_head parses quoted multipart parameters such as Content-Disposition: form-data; name="..." using repeated String#index searches combined with String#slice! prefix deletion. For escape-heavy quoted values, this causes super-linear processing. An unauthenticated attacker can send a crafted multipart/form-data request containing many parts with long backslash-escaped parameter values to trigger excessive CPU usage during multipart parsing. This results in a denial of service condition in Rack applications that accept multipart form data. This issue has been patched in versions 3.1.21 and 3.2.6.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: 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
Severity75% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
40%
KEV
Not listed

Published

April 2, 2026

Last Modified

July 24, 2026

Advisory Details (4)

Auto-updated Jul 3, 2026
Patch available. Sources: github, redhat.
redhat

Affected: Red Hat Enterprise Linux 10",

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-34827.json
redhat

2454501 – (CVE-2026-34827) CVE-2026-34827 rack: Rack: Denial of Service via crafted multipart/form-data requests

https://bugzilla.redhat.com/show_bug.cgi?id=2454501
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-34827
github Patch Available

Multipart header parsing allows denial of service via escape-heavy quoted parameters. · Advisory · rack/rack · GitHub

https://github.com/rack/rack/security/advisories/GHSA-v6x5-cg8r-vv6x

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubunturuby-rack (2.2.7-1ubuntu0.7) @ noble2026-07-26ubuntu

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

(3 across 3 ecosystems)
Debian:13(1)
PackageVulnerable rangeFixed inDependents
ruby-rack3.1.16-0.1 ... 3.2.6-3 (10 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
ruby-rack3.1.16-0.1 ... 3.2.6-1 (7 versions)3.2.6-2—
RubyGems(1)
PackageVulnerable rangeFixed inDependents
rack3.2.0 ... 3.2.5 (6 versions)3.2.6—

Weakness Classification(3)

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

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 7× in last 7d / 29× 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 188 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-34827?
CVE-2026-34827 is a high vulnerability published on April 2, 2026. Rack is a modular Ruby web server interface. From versions 3.0.0.beta1 to before 3.1.21, and 3.2.0 to before 3.2.6, Rack::Multipart::Parser#handlemimehead parses quoted multipart parameters such as Content-Disposition: form-data; name="..." using repeated String#index searches combined with…
When was CVE-2026-34827 disclosed?
CVE-2026-34827 was first published in the National Vulnerability Database on April 2, 2026, with the most recent update on July 24, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-34827 actively exploited?
CVE-2026-34827 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 60.3% of all scored CVEs.
What is the CVSS score of CVE-2026-34827?
CVE-2026-34827 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-34827?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-34827, 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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