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CVE-2026-34826

medium

Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Utils.get_byte_ranges parses the HTTP Range header without limiting the number of individual byte ranges. Although the existing fix for CVE-2024-26141 rejects ranges whose total byte coverage exceeds the file size, it does not restrict the count of ranges. An attacker can supply many small overlapping ranges such as 0-0,0-0,0-0,... to trigger disproportionate CPU, memory, I/O, and bandwidth consumption per request. This results in a denial of service condition in Rack file-serving paths that process multipart byte range responses. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.

5.3
cvss medium
common vulnerability scoring system v3.1. measures intrinsic severity on a 0-10 scale.
epss 0.0004
exploitation prediction scoring system. probability this vulnerability will be exploited in the wild in the next 30 days.
kev no
cisa known exploited vulnerabilities catalog. confirmed active exploitation.
CVSS 3.1 Common Vulnerability Scoring System v3.1
5.3 / 10
MEDIUM
exploitability
Attack Vector
Network
Attack Vector (AV:N): exploitable remotely over the network — most dangerous. no physical or adjacent access needed.
Attack Complexity
Low
Attack Complexity (AC:L): no special conditions needed. attack can be reliably reproduced.
Privileges Required
None
Privileges Required (PR:N): no authentication needed. any anonymous attacker can exploit this.
User Interaction
None
User Interaction (UI:N): no victim action needed. fully exploitable without user interaction.
impact
Scope
Unchanged
Scope (S:U): impact limited to the vulnerable component.
Confidentiality
None
Confidentiality (C:N): no confidentiality impact.
Integrity
None
Integrity (I:N): no integrity impact.
Availability
Low
Availability (A:L): reduced performance or partial service interruption.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
exploit detect attrib advisory media timeline
exploitation detection attribution advisories media timeline
activity density
rdintel assessment
23 threat composite score from 15+ signals including exploitation status, epss probability, detection coverage, and community attention. 0-100 scale.

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