CVE-2026-80213

MEDIUMPre-NVD 4.04.0
EchelonGraph scoreMEDIUM confidence

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

Score 4.0 from GitHub Security Advisory published 2026-08-27. A secondary CVSS source baseline 4.0; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 4 sources updated this week
4.0EG
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: 0.4%CVSS: 4.0Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

An issue was discovered in the resolv gem before 0.7.2 for Ruby. Resolv::DNS::MessageEncoder wrote a DNS label's length into a single octet without checking its range. A label longer than 255 octets had its length stored modulo 256 but the label data was written unchanged, and thus the bytes on the wire described a different name than the one the application asked to encode. RFC 1035 section 2.3.4 limits a label to 63 octets, and the two high bits of the length octet are reserved for compression pointers. put_string packed the length with put_pack("C", d.length) and put_label used it for labels, and thus any value from 0 to 255 could end up as a label length octet, including the reserved 0x40-0xBF range and the 0xC0-0xFF pointer range. Resolv::DNS::Name.create did not check per-label or total name length either, and thus an attacker-controlled hostname reached the encoder unchanged. An application that resolves an attacker-controlled hostname sends a query whose wire bytes name a domain the attacker chose. A hostname suffix that the application validates against an allowlist becomes padding that never appears on the wire, and thus allowlist and egress checks can be bypassed. The recursive resolver caches the response under the attacker's name, and DNS logs record that name rather than the one the application asked for. A label length whose low octet lands in the 0xC0-0xFF range produces a length octet that conforming parsers read as the start of a compression pointer, with the following attacker-controlled byte as the offset.

CVSS v3
4.0
EG Score
4.0MEDIUMmedium confidence
EG Risk
18
EG Risk 18/100

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed (value × EchelonGraph’s weight)
Severity40% × 45%
The EG Score, 4.0 of 10.
Exploitation0.4% × 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
0.4%
EPSS %ILE
26th
KEV
Not listed

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

August 27, 2026

Last Modified

September 9, 2026

Advisory Details (2)

Auto-updated Aug 27, 2026
Patch available.
Web page

Security advisories: CVE-2026-80212 and CVE-2026-80213 | Ruby

https://www.ruby-lang.org/en/news/2026/08/27/multiple-vulnerabilities-in-resolv/
Web page

GitHub - ruby/resolv: A thread-aware DNS resolver library written in Ruby · GitHub

https://github.com/ruby/resolv

Vendor Advisories for CVE-2026-80213(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
redhatruby3-3-main-0.21.9-23.6.hum12026-09-02redhat
redhatruby4-0-main-0.3.2-37.3.hum12026-09-02redhat
redhatruby3-3-main-3.3.10-23.5.hum12026-08-21redhat
redhatruby3-4-main-3.4.10-31.6.hum12026-08-21redhat
redhatruby4-0-main-4.0.6-37.2.hum12026-08-20redhat

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.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 20× in last 7d / 99× 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 99 of 162 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. 1 repeat row among the latest 100 is merged into the row it repeats. The 63 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  2. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  3. 2026-10-12 14:57 UTCEG score recompute
  4. 2026-10-11 19:21 UTCEG score recompute
  5. 2026-10-11 16:37 UTCEG score recompute
  6. 2026-10-11 13:56 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  9. 2026-10-10 10:02 UTCEG score recompute
  10. 2026-10-10 10:02 UTCVendor advisory
  11. 2026-10-10 10:02 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  12. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  13. 2026-10-09 07:45 UTCEG score recompute
  14. 2026-10-09 07:45 UTCVendor advisory
  15. 2026-10-09 07:45 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  16. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  17. 2026-10-08 05:29 UTCEG score recompute
  18. 2026-10-08 05:29 UTCVendor advisory
  19. 2026-10-08 05:29 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  20. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  21. 2026-10-07 03:11 UTCEG score recompute
  22. 2026-10-07 03:11 UTCVendor advisory
  23. 2026-10-07 03:11 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  24. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  25. 2026-10-06 00:54 UTCEG score recompute
Show 74 more
  1. 2026-10-06 00:54 UTCVendor advisory
  2. 2026-10-06 00:54 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  3. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  4. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  5. 2026-10-04 19:39 UTCVendor advisory
  6. 2026-10-04 19:39 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  7. 2026-10-03 15:14 UTCEG score recompute
  8. 2026-10-03 15:14 UTCVendor advisory
  9. 2026-10-03 15:14 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  10. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  11. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  12. 2026-10-02 09:37 UTCEG score recompute
  13. 2026-10-02 09:37 UTCVendor advisory
  14. 2026-10-02 09:37 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  15. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  16. 2026-10-01 07:20 UTCEG score recompute
  17. 2026-10-01 07:20 UTCVendor advisory
  18. 2026-10-01 07:20 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  19. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  20. 2026-09-30 05:04 UTCEG score recompute
  21. 2026-09-30 05:04 UTCVendor advisory
  22. 2026-09-30 05:03 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  23. 2026-09-28 23:19 UTCEG score recompute
  24. 2026-09-28 23:19 UTCVendor advisory
  25. 2026-09-28 23:19 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  26. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  27. 2026-09-27 21:02 UTCEG score recompute
  28. 2026-09-27 21:02 UTCVendor advisory
  29. 2026-09-27 21:02 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  30. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  31. 2026-09-26 18:46 UTCEG score recompute
  32. 2026-09-26 18:46 UTCVendor advisory
  33. 2026-09-26 18:46 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  34. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  35. 2026-09-26 00:28 UTCEPSS rescoreEPSS 0.4% · 25th percentile
  36. 2026-09-25 00:13 UTCEG score recompute
  37. 2026-09-25 00:13 UTCVendor advisory
  38. 2026-09-25 00:13 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  39. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.4% · 25th percentile
  40. 2026-09-23 21:55 UTCEG score recompute
  41. 2026-09-23 21:55 UTCVendor advisory
  42. 2026-09-23 21:55 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  43. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  44. 2026-09-22 19:39 UTCEG score recompute
  45. 2026-09-22 19:39 UTCVendor advisory
  46. 2026-09-22 19:39 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  47. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  48. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  49. 2026-09-21 17:21 UTCEG score recompute
  50. 2026-09-21 17:21 UTCVendor advisory
  51. 2026-09-21 17:20 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  52. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  53. 2026-09-20 15:03 UTCEG score recompute
  54. 2026-09-20 15:03 UTCVendor advisory
  55. 2026-09-20 15:02 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  56. 2026-09-19 12:45 UTCEG score recompute
  57. 2026-09-19 12:45 UTCVendor advisory
  58. 2026-09-19 12:45 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  59. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  60. 2026-09-18 10:29 UTCEG score recompute
  61. 2026-09-18 10:29 UTCVendor advisory
  62. 2026-09-18 10:29 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  63. 2026-09-17 08:13 UTCEG score recompute
  64. 2026-09-17 08:13 UTCVendor advisory
  65. 2026-09-17 08:13 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  66. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  67. 2026-09-16 05:55 UTCEG score recompute
  68. 2026-09-16 05:55 UTCVendor advisory
  69. 2026-09-16 05:55 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  70. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.4% · 28th percentile
  71. 2026-09-15 03:38 UTCEG score recompute
  72. 2026-09-15 03:38 UTCVendor advisory
  73. 2026-09-15 03:38 UTCGHSA enrichmentGHSA-jr95-x3fr-rcg4 · GitHub CVSS 4.0
  74. 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.4% · 28th percentile

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-80213?
CVE-2026-80213 is a medium-severity vulnerability; its CVE record was published on August 27, 2026. An issue was discovered in the resolv gem before 0.7.2 for Ruby. Resolv::DNS::MessageEncoder wrote a DNS label's length into a single octet without checking its range. A label longer than 255 octets had its length stored modulo 256 but the label data was written unchanged, and thus the bytes on the…
When was the CVE record for CVE-2026-80213 published?
The CVE record for CVE-2026-80213 was published on August 27, 2026. 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 September 9, 2026; the record at its source may have been updated since.
Is CVE-2026-80213 actively exploited?
CVE-2026-80213 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (26th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-80213?
CVE-2026-80213 has a CVSS base score of 4.0 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-80213?
A fix for CVE-2026-80213 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-80213 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

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