5.3

CVE-2026-34786: rack

CVSS: 5.3v3.1MediumAnalyzed
AliasesUBUNTU-CVE-2026-34786DEBIAN-CVE-2026-34786CGA-29c4-2qjv-g6r5
Published 02-04-2026Last modified 03-04-2026
Open JSON

Vulnerability summary

CVE-2026-34786 is a medium (CVSS 5.3) vulnerability in rack. EPSS estimates a 0.33% chance of exploitation in the next 30 days, higher than 24.2% of scored vulnerabilities.

Overall risk
21/100
0100
Low · default modelHow is this calculated?
CVSS score
5.3/10
010
Medium · v3.1 (CVE.org)
EPSS score
0.33%
0%100%
Low · +0.13 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 5 · Related 6
MGASA-2026-0226OPENSUSE-SU-2026:10508-1OPENSUSE-SU-2026:21640-1SUSE-SU-2026:23321-1SUSE-SU-2026:2487-1CGA-H498-JRHC-2QC6

Timeline

  1. 02-04-2026
    PublishedVulnerability first disclosed.
  2. 03-04-2026
    Last modifiedVulnerability information updated.

Description

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 metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.33%

Chance of exploitation in the next 30 days

Percentile

24%

Versus all other CVEs

30-day change

+0.13 pp

From 0.19% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.33%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard57 products
  • gitlab-exporter-18.10< 18.10.3-r0
  • gitlab-exporter-18.7All versions (No fix recorded)
  • gitlab-exporter-18.8< 18.8.9-r0
  • gitlab-exporter-18.9< 18.9.5-r0
  • gitlab-rails-ce-18.1< 18.1.6-r13
Wolfi8 products
  • kube-fluentd-operator< 1.18.2-r60 | < 1.18.2-r67
  • logstash-9.3< 9.3.3-r2
  • logstash-9.3-iamguarded-compat< 9.3.3-r2
  • logstash-9.3-with-output-opensearch< 9.3.3-r2
  • ruby3.2-rack-2.2< 2.2.23-r0
Debian1 product
  • ruby-rack< 2.2.22-0+deb12u2 | < 3.1.20-0+deb13u2 | < 3.2.6-2
Rack1 product
  • rack≥ 3.0.0.beta1, < 3.1.21 | < 2.2.23 | ≥ 3.0.0, < 3.1.21 | ≥ 3.2.0, < 3.2.6
RubyGems1 product
  • rack< 2.2.23 | ≥ 3.0.0.beta1, < 3.1.21 | ≥ 3.2.0, < 3.2.6
Ubuntu1 product
  • ruby-rackAll versions (No fix recorded) | < 1.6.4-4ubuntu0.2+esm10 | < 2.1.4-5ubuntu1.2+esm3 | < 2.2.7-1ubuntu0.7 | < 3.1.16-0.1ubuntu0.3

6 vendors · 69 products

References

9 links