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Vulnerability details: VCID-wvs1-dhwp-ebat
Vulnerability ID VCID-wvs1-dhwp-ebat
Aliases CVE-2026-26961
GHSA-vgpv-f759-9wx3
Summary Rack is a modular Ruby web server interface. Prior to versions 2.2.23, 3.1.21, and 3.2.6, Rack::Multipart::Parser extracts the boundary parameter from multipart/form-data using a greedy regular expression. When a Content-Type header contains multiple boundary parameters, Rack selects the last one rather than the first. In deployments where an upstream proxy, WAF, or intermediary interprets the first boundary parameter, this mismatch can allow an attacker to smuggle multipart content past upstream inspection and have Rack parse a different body structure than the intermediary validated. This issue has been patched in versions 2.2.23, 3.1.21, and 3.2.6.
Status Published
Exploitability 0.5
Weighted Severity 3.3
Risk 1.6
Affected and Fixed Packages Package Details
Weaknesses (2)
CWE-436 Interpretation Conflict
CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
System Score Found at
cvssv3 3.7 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-26961.json
epss 0.00029 https://api.first.org/data/v1/epss?cve=CVE-2026-26961
epss 0.00029 https://api.first.org/data/v1/epss?cve=CVE-2026-26961
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-26961
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-26961
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-26961
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-26961
epss 0.00038 https://api.first.org/data/v1/epss?cve=CVE-2026-26961
cvssv3.1 3.7 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
cvssv3.1_qr LOW https://github.com/advisories/GHSA-vgpv-f759-9wx3
cvssv3.1 3.7 https://github.com/rack/rack
generic_textual LOW https://github.com/rack/rack
cvssv3.1 3.7 https://github.com/rack/rack/security/advisories/GHSA-vgpv-f759-9wx3
cvssv3.1_qr LOW https://github.com/rack/rack/security/advisories/GHSA-vgpv-f759-9wx3
generic_textual LOW https://github.com/rack/rack/security/advisories/GHSA-vgpv-f759-9wx3
ssvc Track https://github.com/rack/rack/security/advisories/GHSA-vgpv-f759-9wx3
cvssv3.1 3.7 https://nvd.nist.gov/vuln/detail/CVE-2026-26961
generic_textual LOW https://nvd.nist.gov/vuln/detail/CVE-2026-26961
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-26961.json
https://api.first.org/data/v1/epss?cve=CVE-2026-26961
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-26961
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
https://github.com/rack/rack
https://github.com/rack/rack/security/advisories/GHSA-vgpv-f759-9wx3
https://nvd.nist.gov/vuln/detail/CVE-2026-26961
2454483 https://bugzilla.redhat.com/show_bug.cgi?id=2454483
GHSA-vgpv-f759-9wx3 https://github.com/advisories/GHSA-vgpv-f759-9wx3
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-26961.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://github.com/rack/rack
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://github.com/rack/rack/security/advisories/GHSA-vgpv-f759-9wx3
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: SSVCv2/E:N/A:N/T:P/P:M/B:A/M:M/D:T/2026-04-03T17:57:50Z/ Found at https://github.com/rack/rack/security/advisories/GHSA-vgpv-f759-9wx3
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Found at https://nvd.nist.gov/vuln/detail/CVE-2026-26961
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.08219
EPSS Score 0.00029
Published At April 4, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-04-03T07:52:21.291323+00:00 Debian Importer Import https://security-tracker.debian.org/tracker/data/json 38.1.0