CVE-2026-56416

MEDIUMPre-NVD 4.84.8
EchelonGraph scoreMEDIUM confidence

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

Score 4.8 from GitHub Security Advisory published 2026-07-22. A secondary CVSS source baseline 4.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source

Also known asEUVD-2026-47684 (ENISA EUVD) · GHSA-2845-97v4-7wm3 (GitHub Security Advisories)Source: ENISA EUVD

4.8EG
EchelonGraph verdictMonitorRemediate within your standard update timelines (the SSVC decision on this page).
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 4.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

In NLnet Labs Unbound up to and including version 1.25.1, when the validator builds the canonical RDATA form for an RRSIG-covered PX/RP/MINFO/SOA RRset, it computes the address of the second embedded domain name as 'datstart + dname_valid(datstart, ...)' and passes it straight to 'query_dname_tolower()' without checking that a second name is actually present in the RDATA. The wire-format parser accepts multi-dname RRs whose RDATA ends after the first name, so an attacker who runs a DNSSEC-signed authoritative server can deliver a record with an absent second domain name (e.g. SOA record) and cause 'query_dname_tolower()' to walk label-by-label through stale bytes in the per-worker 'env->scratch_buffer', past the end of that heap allocation if 'msg-buffer-size' has been lowered from the default. This leads to heap buffer overflow and on a release build the outcome relies heavily on the contents of the buffer tail and the adjacent heap chunk.

CVSS v3
4.8
EG Score
4.8MEDIUMmedium confidence
EG Risk
22
EG Risk 22/100

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)
Severity48% × 45%
Impact severity (EG Severity): CVSS 4.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.1% × 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
0.1%
EPSS %ILE
2nd
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 (4.8): severity, escalated by confirmed exploitation. This CVE's 4.8 is its impact severity (EG Severity), not escalated.

EG Severity
4.8 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.1% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). 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 Jul 22, 2026
Patch available.
Web page
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-56416.txt

Vendor Advisories for CVE-2026-56416(3)

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

Patch Availability(1)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
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—
  • 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 1.25.2-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.

Data Freshness Timeline

(refreshed 5× in last 7d / 44× 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 269 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 169 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 0.1% · 2nd percentile
  2. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  3. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  4. 2026-10-25 14:18 UTCEG score recompute
  5. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  6. 2026-10-24 13:34 UTCEG score recompute
  7. 2026-10-24 13:34 UTCVendor advisory
  8. 2026-10-24 13:34 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  9. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  10. 2026-10-22 21:09 UTCEG score recompute
  11. 2026-10-22 21:09 UTCVendor advisory
  12. 2026-10-22 21:09 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  13. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  14. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  15. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  16. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  17. 2026-10-18 03:29 UTCEG score recompute
  18. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  19. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  20. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  21. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  22. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  23. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  24. 2026-10-12 15:54 UTCEG score recompute
  25. 2026-10-11 19:38 UTCEG score recompute
Show 75 more
  1. 2026-10-11 16:53 UTCEG score recompute
  2. 2026-10-11 14:16 UTCEG score recompute
  3. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  4. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  5. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.1% · 1st percentile
  6. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  7. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  8. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  9. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  10. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  11. 2026-10-04 13:26 UTCEG score recompute
  12. 2026-10-04 13:26 UTCVendor advisory
  13. 2026-10-04 13:26 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  14. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  15. 2026-10-03 03:34 UTCEG score recompute
  16. 2026-10-03 03:34 UTCVendor advisory
  17. 2026-10-03 03:34 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  18. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  19. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  20. 2026-10-01 06:29 UTCEG score recompute
  21. 2026-10-01 06:29 UTCVendor advisory
  22. 2026-10-01 06:29 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  23. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  24. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  25. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  26. 2026-09-28 05:18 UTCEG score recompute
  27. 2026-09-28 05:18 UTCVendor advisory
  28. 2026-09-28 05:18 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  29. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  30. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  31. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  32. 2026-09-23 22:26 UTCEG score recompute
  33. 2026-09-23 22:26 UTCVendor advisory
  34. 2026-09-23 22:26 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  35. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  36. 2026-09-22 23:59 UTCEG score recompute
  37. 2026-09-22 23:59 UTCVendor advisory
  38. 2026-09-22 23:59 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  39. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  40. 2026-09-20 02:02 UTCEG score recompute
  41. 2026-09-20 02:02 UTCVendor advisory
  42. 2026-09-20 02:02 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  43. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  44. 2026-09-18 03:51 UTCEG score recompute
  45. 2026-09-18 03:51 UTCVendor advisory
  46. 2026-09-18 03:51 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  47. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  48. 2026-09-17 05:27 UTCEG score recompute
  49. 2026-09-17 05:27 UTCVendor advisory
  50. 2026-09-17 05:27 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  51. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  52. 2026-09-16 07:04 UTCEG score recompute
  53. 2026-09-16 07:04 UTCVendor advisory
  54. 2026-09-16 07:04 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  55. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  56. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  57. 2026-09-14 16:55 UTCVendor advisory
  58. 2026-09-14 16:55 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  59. 2026-09-13 17:19 UTCEG score recompute
  60. 2026-09-13 17:19 UTCVendor advisory
  61. 2026-09-13 17:19 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  62. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  63. 2026-09-12 18:56 UTCEG score recompute
  64. 2026-09-12 18:56 UTCVendor advisory
  65. 2026-09-12 18:56 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  66. 2026-09-11 20:28 UTCEG score recompute
  67. 2026-09-11 20:28 UTCVendor advisory
  68. 2026-09-11 20:28 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  69. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  70. 2026-09-10 21:37 UTCEG score recompute
  71. 2026-09-10 21:37 UTCVendor advisory
  72. 2026-09-10 21:37 UTCGHSA enrichmentGHSA-2845-97v4-7wm3 · GitHub CVSS 4.8
  73. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.1% · 2nd percentile
  74. 2026-09-09 09:17 UTCEG score recompute
  75. 2026-09-09 09:17 UTCVendor advisory

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

Frequently asked(5)

What is CVE-2026-56416?
CVE-2026-56416 is a medium-severity vulnerability; its CVE record was published on July 22, 2026. In NLnet Labs Unbound up to and including version 1.25.1, when the validator builds the canonical RDATA form for an RRSIG-covered PX/RP/MINFO/SOA RRset, it computes the address of the second embedded domain name as 'datstart + dnamevalid(datstart, ...)' and passes it straight to…
When was CVE-2026-56416 made public?
CVE-2026-56416 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-2026-56416 actively exploited?
CVE-2026-56416 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (2nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-56416?
CVE-2026-56416 has a CVSS base score of 4.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-56416?
A fix for CVE-2026-56416 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-56416 are linked in the Vendor Advisories panel on this page.

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