CVE-2026-34829

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 79% 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
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.5Exploit: NoneExposed: 0

A fix is available — apply it.

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser only wraps the request body in a BoundedIO when CONTENT_LENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer encoding, multipart parsing continues until end-of-stream with no total size limit. For file parts, the uploaded body is written directly to a temporary file on disk rather than being constrained by the buffered in-memory upload limit. An unauthenticated attacker can therefore stream an arbitrarily large multipart file upload and consume unbounded disk space. This results in a denial of service condition for Rack applications that accept multipart form data. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

CVSS v3
7.5
EG Score
7.5(medium)
EPSS
29.4%
KEV
Not listed

Published

April 2, 2026

Last Modified

July 15, 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-2026-34829.json
redhat

2454488 – (CVE-2026-34829) CVE-2026-34829 rack: Rack: Denial of Service via unbounded multipart file upload

https://bugzilla.redhat.com/show_bug.cgi?id=2454488
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-34829
github Patch Available

Multipart parsing without `Content-Length` header allows unbounded chunked file uploads. · Advisory · rack/rack · GitHub

https://github.com/rack/rack/security/advisories/GHSA-8vqr-qjwx-82mw

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubunturuby-rack (1.6.4-3ubuntu0.2+esm10) @ xenial2026-06-11ubuntu

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

(1 across 1 ecosystem)
RubyGems(1)
PackageVulnerable rangeFixed inDependents
rack3.2.0 ... 3.2.5 (6 versions)3.2.6—

Weakness Classification(2)

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 8× in last 7d / 37× 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 102 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-34829?
CVE-2026-34829 is a high vulnerability published on April 2, 2026. Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser only wraps the request body in a BoundedIO when CONTENT_LENGTH is present. When a multipart/form-data request is sent without a Content-Length header, such as with HTTP chunked transfer…
When was CVE-2026-34829 disclosed?
CVE-2026-34829 was first published in the National Vulnerability Database on April 2, 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-2026-34829 actively exploited?
CVE-2026-34829 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 29.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-34829?
CVE-2026-34829 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-34829?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-34829, 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-2026-34829

Explore →

Is Your Infrastructure Affected by CVE-2026-34829?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs