CVE-2026-34827

HIGHPre-NVD 7.57.5
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (41st percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
Trending — 3 sources updated this week

Also known asEUVD-2026-18474 (ENISA EUVD)Source: ENISA EUVD

7.5EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 7.5Exploit: None knownExposed services: Not assessed

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
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity75% × 45%
Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.7% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
41st
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.

EG Severity
7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS. FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

April 2, 2026

Last Modified

July 24, 2026

Advisory Details (4)

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

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
Red HatMentions a patch (unverified)

cve-details

https://access.redhat.com/security/cve/CVE-2026-34827
GitHub advisoryMentions a patch (unverified)

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 / EcosystemFix (by version range) / PatchReleasedSource
ubunturuby-rack (2.0.7-2ubuntu0.1+esm10) @ focal2026-10-24ubuntu

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 rangeFix by version rangeDependents
ruby-rack3.1.16-0.1, 3.1.18-1, 3.1.18-1~deb13u1, 3.1.20-0+deb13u1
  • every version up to 3.1.20-0+deb13u2: fixed in 3.1.20-0+deb13u2
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
ruby-rack3.1.16-0.1 ... 3.2.6-1 (7 versions)
  • every version up to 3.2.6-2: fixed in 3.2.6-2
—
RubyGems(1)
PackageVulnerable rangeFix by version rangeDependents
rack3.2.0 ... 3.2.5 (6 versions)
  • 3.0.0.beta1 up to 3.1.21: fixed in 3.1.21
  • 3.2.0 up to 3.2.6: fixed in 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 10× in last 7d / 39× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 99 of 236 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 100 is merged into the row it repeats. The 137 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  2. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  3. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  4. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  5. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  6. 2026-10-25 14:33 UTCEG score recompute
  7. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  8. 2026-10-24 09:13 UTCEG score recompute
  9. 2026-10-24 09:13 UTCVendor advisory
  10. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  11. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  12. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  13. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  14. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  15. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  16. 2026-10-18 03:45 UTCEG score recompute
  17. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  18. 2026-10-17 15:28 UTCEG score recompute
  19. 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  20. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  21. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  22. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  23. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  24. 2026-10-12 16:12 UTCEG score recompute
  25. 2026-10-11 19:54 UTCEG score recompute
Show 74 more
  1. 2026-10-11 17:07 UTCEG score recompute
  2. 2026-10-11 14:34 UTCEG score recompute
  3. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  4. 2026-10-11 02:31 UTCOSV refresh
  5. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.7% · 50th percentile
  6. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  7. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  8. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  9. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  10. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  11. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  12. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  13. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  14. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  15. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  16. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  17. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  18. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.7% · 49th percentile
  19. 2026-09-21 13:49 UTCOSV refresh
  20. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  21. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  22. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  23. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  24. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  25. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  26. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  27. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  28. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  29. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  30. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  31. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  32. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  33. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  34. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  35. 2026-09-02 11:34 UTCOSV refresh
  36. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  37. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  38. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  39. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  40. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  41. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  42. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  43. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  44. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  45. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  46. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  47. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  48. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  49. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  50. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  51. 2026-08-16 09:21 UTCEG score recompute
  52. 2026-08-16 09:21 UTCVendor advisory
  53. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  54. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  55. 2026-08-14 18:53 UTCVendor advisory
  56. 2026-08-14 05:47 UTCEG score recompute
  57. 2026-08-14 05:47 UTCVendor advisory
  58. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  59. 2026-08-13 09:58 UTCVendor advisory
  60. 2026-08-12 20:02 UTCEG score recompute
  61. 2026-08-12 20:02 UTCVendor advisory
  62. 2026-08-12 13:50 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  63. 2026-08-11 20:27 UTCEG score recompute
  64. 2026-08-11 20:27 UTCVendor advisory
  65. 2026-08-11 03:29 UTCEG score recompute
  66. 2026-08-11 03:29 UTCVendor advisory
  67. 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  68. 2026-08-10 03:07 UTCVendor advisory
  69. 2026-08-09 16:12 UTCEG score recompute
  70. 2026-08-09 16:12 UTCVendor advisory
  71. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  72. 2026-08-09 05:18 UTCEG score recompute
  73. 2026-08-09 05:18 UTCVendor advisory
  74. 2026-08-08 16:37 UTCEPSS rescoreEPSS 0.5% · 38th percentile

Frequently asked(5)

What is CVE-2026-34827?
CVE-2026-34827 is a high-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-34827 published?
The CVE record for CVE-2026-34827 was published on April 2, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of July 24, 2026; the record at its source may have been updated since.
Is CVE-2026-34827 actively exploited?
CVE-2026-34827 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (41st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-34827?
CVE-2026-34827 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-34827?
A fix for CVE-2026-34827 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

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