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CVE-2026-34830

26
FAUCET Score

CVE-2026-34830 is a medium-severity vulnerability affecting Rack versions prior to 2.2.23, 3.1.21, and 3.2.6, specifically within the Rack::Sendfile component when used with x-accel-redirect. It stems from unescaped regular expression interpolation, allowing an attacker to inject metacharacters via the X-Accel-Mapping header. This network-based attack, with high complexity, could lead to Nginx serving unintended internal files, resulting in a high confidentiality impact (CVSS 5.9). Currently, there is no evidence of active exploitation, public exploit code, or significant community discussion for this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 2.2.23CPE matchmatch criteria
cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*
>= 3.0.0, < 3.1.21CPE matchmatch criteria
cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*
>= 3.2.0, < 3.2.6CPE matchmatch criteria
cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*

CVSS Data

CVSS version used by this source: 3.1

5.9MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.2
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.21%
Probability of exploitation in next 30 days
EPSS Percentile
11.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0021 is in the 1st percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (11)

rubygemspatch availablevia ghsa
Product: rackFixed in: 3.1.21
rubygemspatch availablevia ghsa
Product: rackFixed in: 3.2.6
rubygemspatch availablevia ghsa
Product: rackFixed in: 2.2.23
ubuntupatch availablevia ubuntu_usn
Product: ruby-rack (jammy)Fixed in: 2.1.4-5ubuntu1.2+esm3
ubuntupatch availablevia ubuntu_usn
Product: ruby-rack (noble)Fixed in: 2.2.7-1ubuntu0.7
ubuntupatch availablevia ubuntu_usn
Product: ruby-rack (questing)Fixed in: 3.1.16-0.1ubuntu0.3
ubuntupatch availablevia ubuntu_usn
Product: ruby-rack (trusty)Fixed in: 1.5.2-3+deb8u3ubuntu1~esm11
ubuntupatch availablevia ubuntu_usn
Product: ruby-rack (xenial)Fixed in: 1.6.4-3ubuntu0.2+esm10
ubuntupatch availablevia ubuntu_usn
Product: ruby-rack (bionic)Fixed in: 1.6.4-4ubuntu0.2+esm10
ubuntupatch availablevia ubuntu_usn
Product: ruby-rack (focal)Fixed in: 2.0.7-2ubuntu0.1+esm10
github_advisoryvendor investigatingvia nvd_reference
View patch

Vendor Advisories (2)

ubuntuUSN-8182-1

Rack vulnerabilities

Apr 17, 2026
rubygemsGHSA-qv7j-4883-hwh7medium

Rack::Sendfile header-based X-Accel-Mapping regex injection enables unauthorized X-Accel-Redirect

Apr 2, 2026

References

github.com / rack/rack/security/advisories/GHSA-qv7j-4883-hwh7
Vendor Advisory