CVE-2025-61921

HIGHNVD 7.57.5
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.5% (42nd percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3
Trending — 4 sources updated this week

Also known asEUVD-2025-33767 (ENISA EUVD) · GHSA-mr3q-g2mv-mr4q (GitHub Security Advisories)Source: ENISA EUVD

7.5EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.5%CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Sinatra is a domain-specific language for creating web applications in Ruby. In versions prior to 4.2.0, 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. Carefully crafted input can cause If-Match and If-None-Match header parsing in Sinatra to take an unexpected amount of time, possibly resulting in a denial of service attack vector. This header is typically involved in generating the ETag header value. Any applications that use the etag method when generating a response are impacted. Version 4.2.0 fixes the issue.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
49
EG Risk 49/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity75% × 45%
Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.5% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.5%
EPSS %ILE
42nd
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.

EG Severity
7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; 60 days if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

October 10, 2025

Last Modified

October 19, 2026

Advisory Details (5)

Auto-updated Oct 18, 2026
Patch available. Sources: github_pr, github.
GitHub advisoryMentions a patch (unverified)

ReDoS vulnerability in ETag generation · Advisory · sinatra/sinatra · GitHub

https://github.com/sinatra/sinatra/security/advisories/GHSA-mr3q-g2mv-mr4q
GitHub pull request

Fix regex in `etag_matches?` to prevent ReDoS

Fix merged in sinatra/sinatra PR #2121 on 2025-10-08 — awaiting tagged release

https://github.com/sinatra/sinatra/pull/2121
GitHub pull request

fix ReDoS

Fix merged in sinatra/sinatra PR #1823 on 2022-10-09 — awaiting tagged release

https://github.com/sinatra/sinatra/pull/1823
Web page

Improvement suggestion · Issue #2120 · sinatra/sinatra · GitHub

https://github.com/sinatra/sinatra/issues/2120
Web page

Feature #19104: Introduce the cache-based optimization for Regexp matching - Ruby - Ruby Issue Tracking System

https://bugs.ruby-lang.org/issues/19104

Patch Availability(2)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubunturuby-sinatra-contrib (2.0.8.1-1ubuntu0.1~esm3) @ focal2026-10-29ubuntu
rubygemssinatra @ 4.2.0 (fixes < 4.2.0)—ghsa

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
ruby-sinatra2.0.8.1-2 ... 4.2.1-5 (19 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
ruby-sinatra3.0.5-3
  • every version up to 3.0.5-3+deb12u1: fixed in 3.0.5-3+deb12u1
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
ruby-sinatra4.1.1-5 ... 4.2.1-5 (7 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
ruby-sinatra4.1.1-5, 4.1.1-6
  • every version up to 4.2.1-1: fixed in 4.2.1-1
—
RubyGems(1)
PackageVulnerable rangeFix by version rangeDependents
sinatra0.1.0 ... 4.1.1 (106 versions)
  • every version up to 4.2.0: fixed in 4.2.0
—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 11× in last 7d / 45× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 96 of 207 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 4 repeat rows among the latest 100 are merged into the row they repeat. The 111 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 16:43 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  2. 2026-11-01 16:33 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  3. 2026-11-01 08:02 UTCGHSA enrichmentGHSA-mr3q-g2mv-mr4q · GitHub severity LOW
  4. 2026-11-01 08:02 UTCEG score recompute
  5. 2026-10-31 16:31 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  6. 2026-10-30 16:33 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  7. 2026-10-29 17:23 UTCEG score recompute
  8. 2026-10-29 17:23 UTCVendor advisory
  9. 2026-10-29 16:32 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  10. 2026-10-28 16:30 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  11. 2026-10-27 16:30 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  12. 2026-10-26 16:30 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  13. 2026-10-25 16:31 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  14. 2026-10-25 16:14 UTCEG score recompute
  15. 2026-10-24 16:31 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  16. 2026-10-23 16:30 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  17. 2026-10-22 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  18. 2026-10-22 11:31 UTCEG score recompute
  19. 2026-10-22 11:31 UTCVendor advisory
  20. 2026-10-21 16:31 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  21. 2026-10-20 16:31 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  22. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  23. 2026-10-19 16:29 UTCEG score recompute
  24. 2026-10-19 16:29 UTCVendor advisory
  25. 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.5% · 41st percentile
Show 71 more
  1. 2026-10-18 05:22 UTCEG score recompute
  2. 2026-10-18 02:32 UTCEG score recompute
  3. 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  4. 2026-10-16 16:39 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  5. 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  6. 2026-10-14 16:31 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  7. 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  8. 2026-10-12 16:51 UTCEG score recompute
  9. 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  10. 2026-10-11 20:26 UTCEG score recompute
  11. 2026-10-11 18:37 UTCEG score recompute
  12. 2026-10-11 15:13 UTCEG score recompute
  13. 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  14. 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  15. 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  16. 2026-10-08 17:10 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  17. 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  18. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  19. 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  20. 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  21. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  22. 2026-10-02 02:41 UTCOSV refresh
  23. 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  24. 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  25. 2026-09-29 15:20 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  26. 2026-09-28 13:50 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  27. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  28. 2026-09-24 14:02 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  29. 2026-09-23 13:47 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  30. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  31. 2026-09-19 15:42 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  32. 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  33. 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  34. 2026-09-16 14:07 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  35. 2026-09-15 03:10 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  36. 2026-09-13 16:46 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  37. 2026-09-12 20:36 UTCOSV refresh
  38. 2026-09-12 15:00 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  39. 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  40. 2026-09-11 09:36 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  41. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  42. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  43. 2026-09-07 16:00 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  44. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  45. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  46. 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  47. 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  48. 2026-08-30 19:16 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  49. 2026-08-30 01:21 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  50. 2026-08-28 21:40 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  51. 2026-08-27 14:24 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  52. 2026-08-26 14:45 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  53. 2026-08-25 13:48 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  54. 2026-08-25 01:26 UTCOSV refresh
  55. 2026-08-24 14:16 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  56. 2026-08-23 00:18 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  57. 2026-08-21 23:48 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  58. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  59. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  60. 2026-08-18 13:47 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  61. 2026-08-17 13:46 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  62. 2026-08-16 14:55 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  63. 2026-08-16 02:13 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  64. 2026-08-15 01:29 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  65. 2026-08-13 21:59 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  66. 2026-08-12 13:50 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  67. 2026-08-11 13:42 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  68. 2026-08-10 23:59 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  69. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.5% · 37th percentile
  70. 2026-08-08 18:55 UTCOSV refresh
  71. 2026-08-08 16:36 UTCEPSS rescoreEPSS 0.5% · 37th percentile

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Frequently asked(5)

What is CVE-2025-61921?
CVE-2025-61921 is a high-severity vulnerability; its CVE record was published on October 10, 2025. Sinatra is a domain-specific language for creating web applications in Ruby. In versions prior to 4.2.0, 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. Carefully crafted…
When was the CVE record for CVE-2025-61921 published?
The CVE record for CVE-2025-61921 was published on October 10, 2025. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of October 19, 2026; the record at its source may have been updated since.
Is CVE-2025-61921 actively exploited?
CVE-2025-61921 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (42nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2025-61921?
CVE-2025-61921 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2025-61921?
A fix for CVE-2025-61921 is available: update to the fixed version the vendor names in its advisory.

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