A multi-vendor cache poisoning vulnerability named 'Rebirthday Attack' has been discovered in caching resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS support, i.e., '--enable-subnet', AND configured to send ECS information along with queries to upstream name servers, i.e., at least one of the 'send-client-subnet', 'client-subnet-zone' or 'client-subnet-always-forward' options is used. Resolvers supporting ECS need to segregate outgoing queries to accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous replies.
CVE-2025-5994
“—” beside the score: it is equal to NVD's CVSS score.
This high-severity CVE scores 8.7 under NVD CVSS v3. EPSS exploit probability: 0.2% (11th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.
- High severity, but no confirmed exploitation yet
A fix is available — apply it.
Fixed versions, as the CVE record's CNA (NLnet Labs) states them: "This issue is fixed in 1.23.1 and all later versions."
- CVSS v3
- 8.7
- EG Score
- 8.7HIGHmedium confidence
- EG Risk
- 54EG Risk 54/100
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)Severity87% × 45%Impact severity (EG Severity): CVSS 8.7 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.2% × 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
- 0.2%
- EPSS %ILE
- 11th
- 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 (8.7): severity, escalated by confirmed exploitation. This CVE's 8.7 is its impact severity (EG Severity), not escalated.
- EG Severity
- 8.7 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
- 0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-17). 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: 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.
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
July 16, 2025
Last Modified
April 15, 2026
Advisory Details (2)
Auto-updated Sep 1, 2026[SECURITY] [DLA 4280-1] unbound security update
https://lists.debian.org/debian-lts-announce/2025/08/msg00019.htmlVendor Advisories for CVE-2025-5994(10)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2026:67857Red Hat Product SecurityHigh
Red Hat Security Advisory: OpenShift Container Platform 4.15.69 bug fix and security update
- RHSA-2026:62549Red Hat Product SecurityHigh
Red Hat Security Advisory: OpenShift Container Platform 4.16.70 bug fix and security update
- RHSA-2025:19894Red Hat Product SecurityHigh
Red Hat Security Advisory: OpenShift Container Platform 4.12.82 bug fix and security update
- RHSA-2025:19041Red Hat Product SecurityHigh
Red Hat Security Advisory: OpenShift Container Platform 4.14.58 bug fix and security update
- RHSA-2025:19046Red Hat Product SecurityHigh
Red Hat Security Advisory: OpenShift Container Platform 4.18.27 bug fix and security update
- RHSA-2025:18240Red Hat Product SecurityHigh
Red Hat Security Advisory: OpenShift Container Platform 4.13.61 bug fix and security update
- RHSA-2025:18217Red Hat Product SecurityHigh
Red Hat Security Advisory: OpenShift Container Platform 4.19.17 bug fix and security update
- RHSA-2025:18218Red Hat Product SecurityHigh
Red Hat Security Advisory: OpenShift Container Platform 4.17.42 bug fix and security update
- +2 more
Patch Availability(20)
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
(10 across 10 ecosystems)
Alpine:v3.19(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| unbound | — |
| — |
Alpine:v3.20(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| unbound | — |
| — |
Alpine:v3.21(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| unbound | — |
| — |
Alpine:v3.22(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| unbound | — |
| — |
Alpine:v3.23(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| unbound | — |
| — |
Alpine:v3.24(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| unbound | — |
| — |
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| unbound | 1.13.1-1, 1.13.1-1+deb11u1, 1.13.1-1+deb11u2, 1.13.1-1+deb11u3, 1.13.1-1+deb11u4 |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| unbound | 1.17.1-2, 1.17.1-2+deb12u1, 1.17.1-2+deb12u2 |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| unbound | — |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| unbound | — |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Additional Vendor Advisories
(11)
Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.
- Red HatRHSA-2025:11849IMPORTANT2025-07-16
RHSA-2025:11849 — Important
- Red HatRHSA-2025:11884IMPORTANT2025-07-16
RHSA-2025:11884 — Important
- Red HatRHSA-2025:12064IMPORTANT2025-07-16
RHSA-2025:12064 — Important
- Red HatRHSA-2025:12416IMPORTANT2025-07-16
RHSA-2025:12416 — Important
- Red HatRHSA-2025:12520IMPORTANT2025-07-16
RHSA-2025:12520 — Important
- Red HatRHSA-2025:12523IMPORTANT2025-07-16
RHSA-2025:12523 — Important
- Red HatRHSA-2025:12929IMPORTANT2025-07-16
RHSA-2025:12929 — Important
- Red HatRHSA-2025:13575IMPORTANT2025-07-16
RHSA-2025:13575 — Important
- Red HatRHSA-2025:13576IMPORTANT2025-07-16
RHSA-2025:13576 — Important
- Red HatRHSA-2025:13577IMPORTANT2025-07-16
RHSA-2025:13577 — Important
- UbuntuUSN-7666-1MEDIUM
Unbound vulnerabilities
Data Freshness Timeline
(refreshed 10× in last 7d / 34× 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 92 of 210 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. 8 repeat rows among the latest 100 are merged into the row they repeat. The 118 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-18 16:31 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-18 03:41 UTCEG score recompute
- 2026-10-18 03:41 UTCVendor advisory
- 2026-10-18 03:41 UTCGHSA enrichmentGHSA-xrv5-2wwg-jp3r · GitHub severity HIGH
- 2026-10-17 16:33 UTCEPSS rescoreEPSS 0.2% · 11th percentile
- 2026-10-16 16:39 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-15 16:31 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-14 16:31 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-13 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-12 16:53 UTCEG score recompute
- 2026-10-12 16:33 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-11 20:27 UTCEG score recompute
- 2026-10-11 18:39 UTCEG score recompute
- 2026-10-11 15:14 UTCEG score recompute
- 2026-10-11 13:47 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-10 19:59 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-10 19:03 UTCOSV refresh
- 2026-10-09 20:06 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-08 17:10 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-07 23:47 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-10-05 17:42 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-10-04 23:21 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.2% · 8th percentile
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- 2026-10-01 19:49 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-09-30 15:02 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-09-29 15:20 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-09-28 13:50 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-09-24 14:02 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-09-23 13:47 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-21 06:19 UTCOSV refresh
- 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-19 15:42 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-18 19:27 UTCEPSS rescoreEPSS 0.2% · 10th percentile
- 2026-09-17 19:30 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-09-16 14:07 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-09-15 03:10 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-09-13 16:46 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-09-12 15:00 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-09-11 14:52 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-09-11 09:36 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-09-07 16:00 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-09-02 14:11 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-09-02 04:09 UTCOSV refresh
- 2026-09-01 13:53 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-08-30 19:16 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-08-30 01:21 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-08-28 21:40 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-08-27 14:24 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-08-26 14:45 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-08-25 13:48 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-08-24 14:16 UTCEPSS rescoreEPSS 0.2% · 9th percentile
- 2026-08-21 23:48 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-18 13:47 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-17 13:46 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-16 14:55 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-16 06:29 UTCOSV refresh
- 2026-08-16 02:13 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-15 01:29 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-13 21:59 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-12 13:50 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-11 13:42 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-10 23:59 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-08 16:36 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-07 16:26 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-06 13:46 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-04 15:09 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-04 10:37 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-03 10:35 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-02 02:26 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-08-01 04:15 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-07-31 23:42 UTCOSV refresh
- 2026-07-30 16:27 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-07-30 01:30 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-07-28 15:35 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-07-27 14:12 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-07-26 14:54 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-07-25 14:17 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-07-24 14:17 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-07-23 14:18 UTCEPSS rescoreEPSS 0.2% · 8th percentile
- 2026-07-23 03:00 UTCEG score recompute
- 2026-07-22 14:08 UTCEPSS rescoreEPSS 0.2% · 8th percentile
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownAlpine:v3.19:unbound
Same vendor
10 shownredhat:RHSA-2025:15397 · redhat:RHSA-2025:18217 · redhat:RHSA-2026:62549
Frequently asked(5)
What is CVE-2025-5994?
When was CVE-2025-5994 made public?
Is CVE-2025-5994 actively exploited?
What is the CVSS score of CVE-2025-5994?
How do I remediate CVE-2025-5994?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2025-5994
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