CVE-2026-42534

MEDIUMNVD 5.35.3
EchelonGraph scoreMEDIUM confidence

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

Score 5.3 from GitHub Security Advisory published 2026-05-20. NVD baseline CVSS 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3

Also known asEUVD-2026-31082 (ENISA EUVD) · GHSA-xfcv-gp55-3wpf (GitHub Security Advisories)Source: ENISA EUVD

5.3EG
EchelonGraph verdictMonitorRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 5.3Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the jostle logic that could defeat its purpose and degrade resolution performance. Retransmits of the same query could renew the age of slow running queries and not allow the jostle logic to see them as aged and potential targets for replacement with new queries. An adversary who can query a vulnerable Unbound and who can control a domain name server that replies slowly and/or maliciously to Unbound's queries can exploit the vulnerability and degrade the resolution performance of Unbound. When Unbound's 'num-queries-per-thread' reaches its limit, the jostle logic kicks in. When a new query comes in, half of the available queries that are also slow to resolve are candidates for replacement. The vulnerability then happens because duplicate queries that need resolution would skew the aging result by using the timestamp of the latest duplicate query instead of the original one that started the resolution effort. Cache and local data response performance remains unaffected. Coordinated attacks could raise this to a denial of resolution service. Unbound 1.25.1 contains a patch with a fix to attach an initial, non-updatable start time for incoming queries that allow the jostle logic to work as intended.

CVSS v3
5.3
EG Score
5.3MEDIUMmedium confidence
EG Risk
39
EG Risk 39/100

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)
Severity53% × 45%
Impact severity (EG Severity): CVSS 5.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.7% × 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
0.6%
EPSS %ILE
48th
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 (5.3): severity, escalated by confirmed exploitation. This CVE's 5.3 is its impact severity (EG Severity), not escalated.

EG Severity
5.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.6% within 30 daysSource: FIRST EPSS. 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

May 20, 2026

Last Modified

September 1, 2026

Advisory Details (1)

Auto-updated May 20, 2026
Patch available.

Patch Availability(5)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntuunbound-host (1.24.2-1ubuntu2.1) @ resolute2026-10-23ubuntu
redhatunbound-0:1.16.2-5.12.el8_102026-07-09redhat
redhatunbound-0:1.24.2-3.el9_8.22026-07-08redhat
redhatunbound-0:1.24.2-7.el10_2.22026-07-07redhat
redhatunbound-main-1.25.1-2.hum12026-06-07redhat

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—
  • every version up to 1.25.2-r0: fixed in 1.25.2-r0
—
Alpine:v3.23(1)
PackageVulnerable rangeFix by version rangeDependents
unbound—
  • every version up to 1.25.2-r0: fixed in 1.25.2-r0
—
Alpine:v3.24(1)
PackageVulnerable rangeFix by version rangeDependents
unbound—
  • every version up to 1.25.1-r0: fixed in 1.25.1-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, 1.22.0-2+deb13u1, 1.22.0-2+deb13u2
  • every version up to 1.22.0-2+deb13u3: fixed in 1.22.0-2+deb13u3
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
unbound1.22.0-2 ... 1.25.0-1 (8 versions)
  • every version up to 1.25.1-1: fixed in 1.25.1-1
—

Weakness Classification(2)

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 8× in last 7d / 41× 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 301 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 201 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 16:44 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  2. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  3. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  4. 2026-10-30 17:25 UTCOSV refresh
  5. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  6. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  7. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  8. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  9. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  10. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.6% · 48th percentile
  11. 2026-10-25 14:29 UTCEG score recompute
  12. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.7% · 54th percentile
  13. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  14. 2026-10-23 02:06 UTCEG score recompute
  15. 2026-10-23 02:06 UTCVendor advisory
  16. 2026-10-23 02:05 UTCGHSA enrichmentGHSA-xfcv-gp55-3wpf · GitHub CVSS 5.3
  17. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  18. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.7% · 53rd percentile
  19. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  20. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  21. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  22. 2026-10-18 03:41 UTCEG score recompute
  23. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  24. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  25. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
Show 75 more
  1. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  2. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  3. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  4. 2026-10-12 16:07 UTCEG score recompute
  5. 2026-10-11 19:49 UTCEG score recompute
  6. 2026-10-11 17:03 UTCEG score recompute
  7. 2026-10-11 14:29 UTCEG score recompute
  8. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  9. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  10. 2026-10-10 02:33 UTCOSV refresh
  11. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  12. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  13. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  14. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  15. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  16. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  17. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  18. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  19. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.7% · 52nd percentile
  20. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  21. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.7% · 51st percentile
  22. 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  23. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  24. 2026-09-20 11:51 UTCOSV refresh
  25. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  26. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  27. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  28. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  29. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  30. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.6% · 46th percentile
  31. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  32. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  33. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  34. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  35. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  36. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  37. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  38. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  39. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  40. 2026-09-01 13:47 UTCVendor advisory
  41. 2026-09-01 13:47 UTCGHSA enrichmentGHSA-xfcv-gp55-3wpf · GitHub CVSS 5.3
  42. 2026-09-01 12:21 UTCEG score recompute
  43. 2026-09-01 12:21 UTCVendor advisory
  44. 2026-09-01 12:21 UTCGHSA enrichmentGHSA-xfcv-gp55-3wpf · GitHub CVSS 5.3
  45. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  46. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  47. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  48. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  49. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  50. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  51. 2026-08-25 12:20 UTCEG score recompute
  52. 2026-08-25 12:20 UTCVendor advisory
  53. 2026-08-25 12:20 UTCGHSA enrichmentGHSA-xfcv-gp55-3wpf · GitHub CVSS 5.3
  54. 2026-08-23 16:57 UTCEG score recompute
  55. 2026-08-23 16:57 UTCVendor advisory
  56. 2026-08-23 16:57 UTCGHSA enrichmentGHSA-xfcv-gp55-3wpf · GitHub CVSS 5.3
  57. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  58. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  59. 2026-08-21 22:55 UTCEG score recompute
  60. 2026-08-21 22:55 UTCVendor advisory
  61. 2026-08-21 22:55 UTCGHSA enrichmentGHSA-xfcv-gp55-3wpf · GitHub CVSS 5.3
  62. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  63. 2026-08-20 18:56 UTCEG score recompute
  64. 2026-08-20 18:56 UTCVendor advisory
  65. 2026-08-20 18:56 UTCGHSA enrichmentGHSA-xfcv-gp55-3wpf · GitHub CVSS 5.3
  66. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  67. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  68. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  69. 2026-08-17 09:54 UTCEG score recompute
  70. 2026-08-17 09:54 UTCVendor advisory
  71. 2026-08-17 09:54 UTCGHSA enrichmentGHSA-xfcv-gp55-3wpf · GitHub CVSS 5.3
  72. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.6% · 45th percentile
  73. 2026-08-16 03:30 UTCEG score recompute
  74. 2026-08-16 03:30 UTCVendor advisory
  75. 2026-08-16 03:30 UTCGHSA enrichmentGHSA-xfcv-gp55-3wpf · GitHub CVSS 5.3

Frequently asked(5)

What is CVE-2026-42534?
CVE-2026-42534 is a medium-severity vulnerability; its CVE record was published on May 20, 2026. NLnet Labs Unbound up to and including version 1.25.0 has a vulnerability in the jostle logic that could defeat its purpose and degrade resolution performance. Retransmits of the same query could renew the age of slow running queries and not allow the jostle logic to see them as aged and potential…
When was CVE-2026-42534 made public?
CVE-2026-42534 was made public on May 20, 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 May 20, 2026. EchelonGraph's copy of the record carries a last-modified date of September 1, 2026; the record at its source may have been updated since.
Is CVE-2026-42534 actively exploited?
CVE-2026-42534 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (48th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-42534?
CVE-2026-42534 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-42534?
A fix for CVE-2026-42534 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-42534 are linked in the Vendor Advisories panel on this page.

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