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Vulnerability details: VCID-tax5-a72w-mbhy
Vulnerability ID VCID-tax5-a72w-mbhy
Aliases CVE-2025-61921
GHSA-mr3q-g2mv-mr4q
Summary Sinatra is vulnerable to ReDoS through ETag header value generation There is a denial of service vulnerability in the `If-Match` and `If-None-Match` header parsing component of Sinatra, if the `etag` method is used when constructing the response and you are using Ruby < 3.2.
Status Published
Exploitability 0.5
Weighted Severity 4.8
Risk 2.4
Affected and Fixed Packages Package Details
Weaknesses (4)
CWE-1333 Inefficient Regular Expression Complexity
CWE-400 Uncontrolled Resource Consumption
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
cvssv3 5.3 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2025-61921.json
epss 0.00397 https://api.first.org/data/v1/epss?cve=CVE-2025-61921
epss 0.00397 https://api.first.org/data/v1/epss?cve=CVE-2025-61921
epss 0.00397 https://api.first.org/data/v1/epss?cve=CVE-2025-61921
epss 0.00397 https://api.first.org/data/v1/epss?cve=CVE-2025-61921
epss 0.00397 https://api.first.org/data/v1/epss?cve=CVE-2025-61921
epss 0.00397 https://api.first.org/data/v1/epss?cve=CVE-2025-61921
epss 0.00397 https://api.first.org/data/v1/epss?cve=CVE-2025-61921
epss 0.00397 https://api.first.org/data/v1/epss?cve=CVE-2025-61921
cvssv4 2.7 https://bugs.ruby-lang.org/issues/19104
generic_textual LOW https://bugs.ruby-lang.org/issues/19104
ssvc Track https://bugs.ruby-lang.org/issues/19104
cvssv3.1_qr LOW https://github.com/advisories/GHSA-mr3q-g2mv-mr4q
cvssv4 2.7 https://github.com/rubysec/ruby-advisory-db/blob/master/gems/sinatra/CVE-2025-61921.yml
generic_textual LOW https://github.com/rubysec/ruby-advisory-db/blob/master/gems/sinatra/CVE-2025-61921.yml
cvssv4 2.7 https://github.com/sinatra/sinatra
generic_textual LOW https://github.com/sinatra/sinatra
cvssv4 2.7 https://github.com/sinatra/sinatra/commit/3fe8c38dc405586f7ad8f2ac748aa53e9c3615bd
generic_textual LOW https://github.com/sinatra/sinatra/commit/3fe8c38dc405586f7ad8f2ac748aa53e9c3615bd
cvssv4 2.7 https://github.com/sinatra/sinatra/commit/8ff496bd4877520599e1479d6efead39304edceb
generic_textual LOW https://github.com/sinatra/sinatra/commit/8ff496bd4877520599e1479d6efead39304edceb
cvssv4 2.7 https://github.com/sinatra/sinatra/issues/2120
generic_textual LOW https://github.com/sinatra/sinatra/issues/2120
ssvc Track https://github.com/sinatra/sinatra/issues/2120
cvssv4 2.7 https://github.com/sinatra/sinatra/pull/1823
generic_textual LOW https://github.com/sinatra/sinatra/pull/1823
ssvc Track https://github.com/sinatra/sinatra/pull/1823
cvssv4 2.7 https://github.com/sinatra/sinatra/pull/2121
generic_textual LOW https://github.com/sinatra/sinatra/pull/2121
ssvc Track https://github.com/sinatra/sinatra/pull/2121
cvssv3.1_qr LOW https://github.com/sinatra/sinatra/security/advisories/GHSA-mr3q-g2mv-mr4q
cvssv4 2.7 https://github.com/sinatra/sinatra/security/advisories/GHSA-mr3q-g2mv-mr4q
generic_textual LOW https://github.com/sinatra/sinatra/security/advisories/GHSA-mr3q-g2mv-mr4q
ssvc Track https://github.com/sinatra/sinatra/security/advisories/GHSA-mr3q-g2mv-mr4q
cvssv4 2.7 https://nvd.nist.gov/vuln/detail/CVE-2025-61921
generic_textual LOW https://nvd.nist.gov/vuln/detail/CVE-2025-61921
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2025-61921.json
https://api.first.org/data/v1/epss?cve=CVE-2025-61921
https://bugs.ruby-lang.org/issues/19104
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2025-61921
https://github.com/sinatra/sinatra
https://github.com/sinatra/sinatra/commit/3fe8c38dc405586f7ad8f2ac748aa53e9c3615bd
https://github.com/sinatra/sinatra/commit/8ff496bd4877520599e1479d6efead39304edceb
https://github.com/sinatra/sinatra/issues/2120
https://github.com/sinatra/sinatra/pull/1823
https://github.com/sinatra/sinatra/pull/2121
1118290 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1118290
2403178 https://bugzilla.redhat.com/show_bug.cgi?id=2403178
CVE-2025-61921 https://nvd.nist.gov/vuln/detail/CVE-2025-61921
CVE-2025-61921.YML https://github.com/rubysec/ruby-advisory-db/blob/master/gems/sinatra/CVE-2025-61921.yml
GHSA-mr3q-g2mv-mr4q https://github.com/advisories/GHSA-mr3q-g2mv-mr4q
GHSA-mr3q-g2mv-mr4q https://github.com/sinatra/sinatra/security/advisories/GHSA-mr3q-g2mv-mr4q
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2025-61921.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

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unchanged

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U Found at https://bugs.ruby-lang.org/issues/19104
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

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Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2025-10-10T20:54:24Z/ Found at https://bugs.ruby-lang.org/issues/19104
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U Found at https://github.com/rubysec/ruby-advisory-db/blob/master/gems/sinatra/CVE-2025-61921.yml
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

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physical

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passive

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U Found at https://github.com/sinatra/sinatra
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

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present

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passive

active

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U Found at https://github.com/sinatra/sinatra/commit/3fe8c38dc405586f7ad8f2ac748aa53e9c3615bd
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

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passive

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U Found at https://github.com/sinatra/sinatra/commit/8ff496bd4877520599e1479d6efead39304edceb
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

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passive

active

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U Found at https://github.com/sinatra/sinatra/issues/2120
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

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Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2025-10-10T20:54:24Z/ Found at https://github.com/sinatra/sinatra/issues/2120
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U Found at https://github.com/sinatra/sinatra/pull/1823
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

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present

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passive

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Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2025-10-10T20:54:24Z/ Found at https://github.com/sinatra/sinatra/pull/1823
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U Found at https://github.com/sinatra/sinatra/pull/2121
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

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present

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passive

active

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Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2025-10-10T20:54:24Z/ Found at https://github.com/sinatra/sinatra/pull/2121
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U Found at https://github.com/sinatra/sinatra/security/advisories/GHSA-mr3q-g2mv-mr4q
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

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passive

active

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low

none

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Vector: SSVCv2/E:N/A:Y/T:P/P:M/B:A/M:M/D:T/2025-10-10T20:54:24Z/ Found at https://github.com/sinatra/sinatra/security/advisories/GHSA-mr3q-g2mv-mr4q
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U Found at https://nvd.nist.gov/vuln/detail/CVE-2025-61921
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

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passive

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Exploit Prediction Scoring System (EPSS)
Percentile 0.60438
EPSS Score 0.00397
Published At April 2, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-04-01T12:52:59.457235+00:00 GitLab Importer Import https://gitlab.com/gitlab-org/advisories-community/-/blob/main/gem/sinatra/CVE-2025-61921.yml 38.0.0