7.5

CVE-2026-34830: rack Permissive Regular Expression

CVSS: 7.5v3.1HighAnalyzed
AliasesUBUNTU-CVE-2026-34830DEBIAN-CVE-2026-34830CGA-24qp-jxjx-9gr3
Published 02-04-2026Last modified 02-04-2026
Open JSON

Vulnerability summary

CVE-2026-34830 is a high (CVSS 7.5) Permissive Regular Expression vulnerability in rack. EPSS estimates a 0.40% chance of exploitation in the next 30 days, higher than 32.5% of scored vulnerabilities.

Overall risk
30/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (NVD)
EPSS score
0.40%
0%100%
Low · +0.16 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-5926-72FF-MP26

Timeline

  1. 02-04-2026
    PublishedVulnerability first disclosed.
  2. 02-04-2026
    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::Sendfile#map_accel_path interpolates the value of the X-Accel-Mapping request header directly into a regular expression when rewriting file paths for X-Accel-Redirect. Because the header value is not escaped, an attacker who can supply X-Accel-Mapping to the backend can inject regex metacharacters and control the generated X-Accel-Redirect response header. In deployments using Rack::Sendfile with x-accel-redirect, this can allow an attacker to cause nginx to serve unintended files from configured internal locations. 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

0.40%

Chance of exploitation in the next 30 days

Percentile

33%

Versus all other CVEs

30-day change

+0.16 pp

From 0.23% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.40%

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-r67 | < 1.18.2-r60
  • 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) | < 1.6.4-3ubuntu0.2+esm10 | < 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