CVE-2026-50252

CRITICALNVD 9.39.3
EchelonGraph scoreMEDIUM confidence

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

Score 9.3 from GitHub Security Advisory published 2026-07-22. NVD baseline CVSS 9.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 4 sources updated this week

Also known asEUVD-2026-47676 (ENISA EUVD) · GHSA-jfgc-mgqq-r573 (GitHub Security Advisories)Source: ENISA EUVD

9.3EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 9.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

In NLnet Labs Unbound 1.4.22 up to and including 1.25.1, UDP source port is randomized and intended to serve as a secret value that increases the entropy of DNS transactions. When resolver load balancing policies depend on the source port while their outcome is revealed this secrecy is undermined. The vulnerability arises when the load balancing policy is consistent with respect to the incoming source UDP port and IP address while heavily depending on the incoming source UDP port as a randomization source. When the SO_REUSEPORT configuration option is enabled ('so-reuseport: yes') in Unbound (by default), it meets these conditions, making it vulnerable for DNS cache poisoning attacks. Upon startup, Unbound randomly partitions the available UDP source port space into disjoint subsets of (almost) equal size, assigning each subset to a specific worker thread. When an incoming DNS query is received, the kernel’s SO_REUSEPORT load balancing mechanism deterministically assigns the query to a socket associated with a particular thread. All outgoing DNS queries generated during the resolution of that request use source ports selected exclusively from the port subset assigned to the corresponding thread. Since these port subsets are disjoint across threads, the source port observed in a resolver’s outgoing query to an authoritative name server serves as a reliable indicator of the worker thread that processed the original client query. A malicious actor can acquire the mapping between incoming UDP source ports (for a given fixed source IP address) and Unbound worker threads and leverage it to conduct DNS cache poisoning attacks by effectively lowering the random port population per thread.

CVSS v3
9.3
EG Score
9.3CRITICALmedium confidence
EG Risk
42
EG Risk 42/100

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)
Severity93% × 45%
Impact severity (EG Severity): CVSS 9.3 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.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (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.
EPSS PROB
0.2%
EPSS %ILE
6th
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 (9.3): severity, escalated by confirmed exploitation. This CVE's 9.3 is its impact severity (EG Severity), not escalated.

EG Severity
9.3 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.2% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-29). 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 every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade 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 every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (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)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable no (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 22, 2026

Last Modified

October 24, 2026

Advisory Details (1)

Auto-updated Oct 8, 2026
Patch available.
Web page
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-50252.txt

Vendor Advisories for CVE-2026-50252(6)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(5)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntuunbound-host (1.19.2-1ubuntu3.12) @ noble2026-10-29ubuntu
redhatunbound-0:1.16.2-5.14.el8_10.22026-09-21redhat
redhatunbound-0:1.24.2-3.el9_8.62026-09-16redhat
redhatunbound-0:1.24.2-7.el10_2.52026-09-16redhat
redhatunbound-main-1.25.2-0.1.hum12026-07-22redhat

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

(7 across 7 ecosystems)
Alpine:v3.22(1)
PackageVulnerable rangeFix by version rangeDependents
unbound—
  • 1.4.22 up to 1.25.2-r0: fixed in 1.25.2-r0
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
unbound—
  • 1.4.22 up to 1.25.2-r0: fixed in 1.25.2-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
unbound—
  • 1.4.22 up to 1.25.2-r0: fixed in 1.25.2-r0
—
Debian:11(1)
PackageVulnerable rangeFix by version rangeDependents
unbound1.13.1-1 ... 1.25.2-1 (47 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
unbound1.17.1-2 ... 1.26.1-1 (26 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
unbound1.22.0-2 ... 1.26.0-2 (15 versions)
  • every version up to 1.26.1-0+deb13u1: fixed in 1.26.1-0+deb13u1
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
unbound1.22.0-2 ... 1.25.1-1 (9 versions)
  • every version up to 1.25.2-1: fixed in 1.25.2-1
—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

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.

Data Freshness Timeline

(refreshed 28× in last 7d / 96× 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 100 of 684 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. None are among the latest 100 rows. The 584 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  2. 2026-10-30 15:05 UTCEG score recompute
  3. 2026-10-30 15:05 UTCVendor advisory
  4. 2026-10-30 15:05 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  5. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  6. 2026-10-29 14:28 UTCEG score recompute
  7. 2026-10-29 14:28 UTCVendor advisory
  8. 2026-10-29 14:28 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  9. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  10. 2026-10-28 13:50 UTCEG score recompute
  11. 2026-10-28 13:50 UTCVendor advisory
  12. 2026-10-28 13:49 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  13. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  14. 2026-10-27 12:57 UTCEG score recompute
  15. 2026-10-27 12:57 UTCVendor advisory
  16. 2026-10-27 12:56 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  17. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  18. 2026-10-26 15:24 UTCEG score recompute
  19. 2026-10-26 15:24 UTCVendor advisory
  20. 2026-10-26 15:24 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  21. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  22. 2026-10-25 14:05 UTCEG score recompute
  23. 2026-10-25 14:05 UTCVendor advisory
  24. 2026-10-25 14:04 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  25. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
Show 75 more
  1. 2026-10-24 13:26 UTCEG score recompute
  2. 2026-10-24 13:26 UTCVendor advisory
  3. 2026-10-24 13:26 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  4. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  5. 2026-10-23 14:04 UTCEG score recompute
  6. 2026-10-23 14:04 UTCVendor advisory
  7. 2026-10-23 14:04 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  8. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  9. 2026-10-22 13:26 UTCEG score recompute
  10. 2026-10-22 13:26 UTCVendor advisory
  11. 2026-10-22 13:26 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  12. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  13. 2026-10-21 12:46 UTCEG score recompute
  14. 2026-10-21 12:46 UTCVendor advisory
  15. 2026-10-21 12:46 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  16. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.2% · 6th percentile
  17. 2026-10-20 12:08 UTCEG score recompute
  18. 2026-10-20 12:08 UTCVendor advisory
  19. 2026-10-20 12:07 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  20. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  21. 2026-10-19 11:26 UTCEG score recompute
  22. 2026-10-19 11:26 UTCVendor advisory
  23. 2026-10-19 11:25 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  24. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  25. 2026-10-18 09:03 UTCVendor advisory
  26. 2026-10-18 09:03 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  27. 2026-10-18 03:33 UTCEG score recompute
  28. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  29. 2026-10-17 08:04 UTCEG score recompute
  30. 2026-10-17 08:04 UTCVendor advisory
  31. 2026-10-17 08:04 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  32. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  33. 2026-10-16 07:25 UTCEG score recompute
  34. 2026-10-16 07:25 UTCVendor advisory
  35. 2026-10-16 07:25 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  36. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  37. 2026-10-15 06:20 UTCEG score recompute
  38. 2026-10-15 06:20 UTCVendor advisory
  39. 2026-10-15 06:20 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  40. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  41. 2026-10-14 02:01 UTCEG score recompute
  42. 2026-10-14 02:01 UTCVendor advisory
  43. 2026-10-14 02:01 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  44. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  45. 2026-10-12 22:19 UTCEG score recompute
  46. 2026-10-12 22:19 UTCVendor advisory
  47. 2026-10-12 22:18 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  48. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  49. 2026-10-12 15:59 UTCEG score recompute
  50. 2026-10-12 07:16 UTCVendor advisory
  51. 2026-10-12 07:16 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  52. 2026-10-11 19:42 UTCEG score recompute
  53. 2026-10-11 16:57 UTCEG score recompute
  54. 2026-10-11 14:21 UTCEG score recompute
  55. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  56. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  57. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  58. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  59. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  60. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  61. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 5th percentile
  62. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  63. 2026-10-04 13:26 UTCVendor advisory
  64. 2026-10-04 13:26 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  65. 2026-10-03 03:34 UTCEG score recompute
  66. 2026-10-03 03:34 UTCVendor advisory
  67. 2026-10-03 03:34 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  68. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  69. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 4th percentile
  70. 2026-10-01 15:21 UTCVendor advisory
  71. 2026-10-01 15:21 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  72. 2026-10-01 10:59 UTCVendor advisory
  73. 2026-10-01 10:59 UTCGHSA enrichmentGHSA-jfgc-mgqq-r573 · GitHub CVSS 9.3
  74. 2026-10-01 06:29 UTCEG score recompute
  75. 2026-10-01 06:29 UTCVendor advisory

Related CVEs(same product + same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-50252?
CVE-2026-50252 is a critical-severity vulnerability; its CVE record was published on July 22, 2026. In NLnet Labs Unbound 1.4.22 up to and including 1.25.1, UDP source port is randomized and intended to serve as a secret value that increases the entropy of DNS transactions. When resolver load balancing policies depend on the source port while their outcome is revealed this secrecy is undermined.…
When was CVE-2026-50252 made public?
CVE-2026-50252 was made public on July 22, 2026: that is the date its CVE record's CNA, NLnet Labs, gives for when the vulnerability was made public. The CVE record itself was published on July 22, 2026. EchelonGraph's copy of the record carries a last-modified date of October 24, 2026; the record at its source may have been updated since.
Is CVE-2026-50252 actively exploited?
CVE-2026-50252 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (6th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-50252?
CVE-2026-50252 has a CVSS v3 base score of 9.3 (NVD).
How do I remediate CVE-2026-50252?
A fix for CVE-2026-50252 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-50252 are linked in the Vendor Advisories panel on this page.

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