CVE-2026-34786

MEDIUMNVD 5.35.3
EchelonGraph scoreMEDIUM confidence

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

Score 5.3 from GitHub Security Advisory (severity: MODERATE) published 2026-04-02. NVD baseline CVSS 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3

Also known asEUVD-2026-18384 (ENISA EUVD) · GHSA-q4qf-9j86-f5mh (GitHub Security Advisories)Source: ENISA EUVD

5.3EG
EchelonGraph verdictMonitorRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 5.3Exploit: None knownExposed services: Not assessed

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::Static#applicable_rules evaluates several header_rules types against the raw URL-encoded PATH_INFO, while the underlying file-serving path is decoded before the file is served. As a result, a request for a URL-encoded variant of a static path can serve the same file without the headers that header_rules were intended to apply. In deployments that rely on Rack::Static to attach security-relevant response headers to static content, this can allow an attacker to bypass those headers by requesting an encoded form of the path. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

CVSS v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
39
EG Risk 39/100

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)
Severity53% × 45%
Impact severity (EG Severity): CVSS 5.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.2% × 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
0.2%
EPSS %ILE
10th
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 (5.3): severity, escalated by confirmed exploitation. This CVE's 5.3 is its impact severity (EG Severity), not escalated.

EG Severity
5.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). 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, and whom BOD 26-04 binds: 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.

The score's inputs: 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 (1)

Auto-updated Jul 26, 2026
Patch available. Sources: github.
GitHub advisoryMentions a patch (unverified)

`Rack::Static` `header_rules` bypass via URL-encoded path mismatch. · Advisory · rack/rack · GitHub

https://github.com/rack/rack/security/advisories/GHSA-q4qf-9j86-f5mh

Vendor Advisories for CVE-2026-34786(1)

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

Patch Availability(4)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubunturuby-rack (1.5.2-3+deb8u3ubuntu1~esm11) @ trusty2026-10-23ubuntu
rubygemsrack @ 2.2.23 (fixes < 2.2.23)—ghsa
rubygemsrack @ 3.1.21 (fixes >= 3.0.0.beta1, < 3.1.21)—ghsa
rubygemsrack @ 3.2.6 (fixes >= 3.2.0, < 3.2.6)—ghsa

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

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
ruby-rack2.1.4-3 ... 2.1.4-3+deb11u5 (6 versions)
  • every version up to 2.1.4-3+deb11u6: fixed in 2.1.4-3+deb11u6
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
ruby-rack2.2.13-1~deb12u1 ... 2.2.7-1.1 (7 versions)
  • every version up to 2.2.22-0+deb12u2: fixed in 2.2.22-0+deb12u2
—
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)
  • every version up to 2.2.23: fixed in 2.2.23
  • 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(1)

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 / 32× 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 its CVE.org record (CNA or CISA ADP). 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). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.

Showing the most recent 100 of 239 rows on record for this CVE, as 99 entries (1 repeat merged).

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 139 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-12 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  2. 2026-11-11 16:39 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  3. 2026-11-10 16:43 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  4. 2026-11-09 16:35 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  5. 2026-11-08 16:39 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  6. 2026-11-07 16:39 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  7. 2026-11-06 16:37 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  8. 2026-11-05 16:37 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  9. 2026-11-04 16:35 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  10. 2026-11-03 16:47 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  11. 2026-11-02 16:44 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  12. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  13. 2026-11-01 07:52 UTCGHSA enrichmentGHSA-q4qf-9j86-f5mh · GitHub severity MODERATE · GitHub CVSS 5.3
  14. 2026-11-01 07:52 UTCEchelonGraph re-scored
  15. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  16. 2026-10-30 20:25 UTCOSV refresh
  17. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.2% · 10th percentile
  18. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  19. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  20. 2026-10-27 16:31 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  21. 2026-10-25 16:32 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  22. 2026-10-25 14:33 UTCEchelonGraph re-scored
  23. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  24. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  25. 2026-10-23 03:17 UTCEchelonGraph re-scored
Show 74 more
  1. 2026-10-23 03:17 UTCVendor advisory
  2. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  3. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  4. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  5. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  6. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  7. 2026-10-18 03:45 UTCEchelonGraph re-scored
  8. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.3% · 24th percentile
  9. 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  10. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  11. 2026-10-14 16:32 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  12. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  13. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  14. 2026-10-12 16:12 UTCEchelonGraph re-scored
  15. 2026-10-11 19:54 UTCEchelonGraph re-scored
  16. 2026-10-11 17:07 UTCEchelonGraph re-scored
  17. 2026-10-11 14:34 UTCEchelonGraph re-scored
  18. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  19. 2026-10-11 02:31 UTCOSV refresh
  20. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  21. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  22. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  23. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  24. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  25. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  26. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  27. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  28. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  29. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  30. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  31. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  32. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.3% · 23rd percentile
  33. 2026-09-26 00:26 UTCEPSS rescoreEPSS 0.3% · 22nd percentile
  34. 2026-09-21 14:19 UTCOSV refresh
  35. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  36. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  37. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  38. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  39. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  40. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  41. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  42. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  43. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  44. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  45. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  46. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  47. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  48. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  49. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  50. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  51. 2026-09-02 11:34 UTCOSV refresh
  52. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  53. 2026-09-01 04:39 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  54. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  55. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  56. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  57. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  58. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  59. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  60. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  61. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  62. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  63. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  64. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  65. 2026-08-16 09:23 UTCEchelonGraph re-scored
  66. 2026-08-16 09:23 UTCVendor advisory
  67. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  68. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  69. 2026-08-14 05:49 UTCEchelonGraph re-scored
  70. 2026-08-14 05:49 UTCVendor advisory
  71. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.2% · 9th percentile
  72. 2026-08-12 20:07 UTCEchelonGraph re-scored
  73. 2026-08-12 20:07 UTCVendor advisory
  74. 2026-08-12 13:50 UTCEPSS rescoreEPSS 0.2% · 9th percentile

Frequently asked(5)

What is CVE-2026-34786?
CVE-2026-34786 is a medium-severity vulnerability; its CVE record was 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::Static#applicable_rules evaluates several header_rules types against the raw URL-encoded PATH_INFO, while the underlying file-serving path is decoded before the file is served. As a result, a request for…
When was the CVE record for CVE-2026-34786 published?
The CVE record for CVE-2026-34786 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-2026-34786 actively exploited?
CVE-2026-34786 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (10th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-34786?
CVE-2026-34786 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-34786?
A fix for CVE-2026-34786 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-34786 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-34786

Explore →

Is Your Infrastructure Affected by CVE-2026-34786?

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