CVE-2026-34830: Rack: Rack::Sendfile regex injection via HTTP_X_ACCEL_MAPPING header allows arbitrary file reads through nginx
Affected: rack · Exploitation: unlikely (under 1%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 15% of scored CVEs
DescriptionCVE.org
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.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- rack · rack< 2.2.23; >= 3.0.0.beta1, < 3.1.21; >= 3.2.0, < 3.2.6
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Unlikely (under 1%). EPSS under 1%, or no score yet.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- rack
- Published
- April 2026
CoverageNo articles yet
No CyberSIXT article names CVE-2026-34830 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.