CVE-2026-42859

HIGHNVD 8.18.1
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 8.1 under NVD CVSS v3. EPSS exploit probability: 0.6% (50th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3

Also known asEUVD-2026-29167 (ENISA EUVD)Source: ENISA EUVD

8.1EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 8.1Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Neat VNC is a VNC server library. Prior to 0.9.6, a pre-authentication stack buffer overflow exists in neatvnc in the RSA-AES security type handler. An unauthenticated remote attacker who can reach the VNC listening socket can send a crafted security type 5 (RSA-AES) or security type 129 (RSA-AES-256) handshake with an oversized client RSA public key, causing rsa_aes_send_challenge in src/auth/rsa-aes.c to overflow a 1024-byte on-stack buffer when encrypting the server challenge. This results in at least a denial of service via server crash. This vulnerability is fixed in 0.9.6.

CVSS v3
8.1
EG Score
8.1HIGHmedium confidence
EG Risk
52
EG Risk 52/100

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)
Severity81% × 45%
Impact severity (EG Severity): CVSS 8.1 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.6% × 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 total (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
50th
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 (8.1): severity, escalated by confirmed exploitation. This CVE's 8.1 is its impact severity (EG Severity), not escalated.

EG Severity
8.1 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
0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-27). 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: 3 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 total (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)3 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 total (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 11, 2026

Last Modified

October 26, 2026

Advisory Details (2)

Auto-updated May 11, 2026
Patch available. Sources: github.
GitHub advisoryMentions a patch (unverified)

Buffer overflow due to oversized RSA public keys · Advisory · any1/neatvnc · GitHub

https://github.com/any1/neatvnc/security/advisories/GHSA-567c-gpv8-qh9h
Web page

auth: rsa-aes: Fix potential buffer overflow · any1/neatvnc@1f6cd6b · GitHub

https://github.com/any1/neatvnc/commit/1f6cd6b75cc167fed3a19a9d1552a1f662f6b337

Affected Packages

(3 across 3 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
neatvnc0.5.4+dfsg-1 ... 1.0.1+dfsg-1 (17 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
neatvnc0.9.1+dfsg-1, 0.9.1+dfsg-1.1, 1.0.0+dfsg-1~exp1, 1.0.1+dfsg-1
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
neatvnc0.9.1+dfsg-1
  • every version up to 0.9.1+dfsg-1.1: fixed in 0.9.1+dfsg-1.1
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 38× 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 193 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 93 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  2. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  3. 2026-10-27 21:00 UTCEG score recompute
  4. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.6% · 50th percentile
  5. 2026-10-26 18:36 UTCEG score recompute
  6. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  7. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.6% · 49th percentile
  8. 2026-10-25 14:29 UTCEG score recompute
  9. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  10. 2026-10-24 13:46 UTCEG score recompute
  11. 2026-10-23 16:31 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  12. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  13. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  14. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  15. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  16. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  17. 2026-10-18 03:40 UTCEG score recompute
  18. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  19. 2026-10-17 14:19 UTCEG score recompute
  20. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  21. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  22. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  23. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  24. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  25. 2026-10-12 16:07 UTCEG score recompute
Show 75 more
  1. 2026-10-11 19:48 UTCEG score recompute
  2. 2026-10-11 17:03 UTCEG score recompute
  3. 2026-10-11 14:29 UTCEG score recompute
  4. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  5. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  6. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  7. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  8. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  9. 2026-10-06 15:17 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  10. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  11. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  12. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  13. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  14. 2026-09-30 06:58 UTCOSV refresh
  15. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  16. 2026-09-26 15:58 UTCEPSS rescoreEPSS 0.8% · 53rd percentile
  17. 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  18. 2026-09-20 20:15 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  19. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  20. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  21. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  22. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  23. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  24. 2026-09-12 15:01 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  25. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  26. 2026-09-11 12:23 UTCOSV refresh
  27. 2026-09-11 09:37 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  28. 2026-09-10 09:34 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  29. 2026-09-08 22:00 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  30. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  31. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.5% · 44th percentile
  32. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  33. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  34. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  35. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  36. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  37. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  38. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  39. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  40. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  41. 2026-08-23 18:38 UTCEG score recompute
  42. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  43. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  44. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  45. 2026-08-19 17:03 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  46. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  47. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  48. 2026-08-17 11:10 UTCEG score recompute
  49. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  50. 2026-08-16 04:25 UTCEG score recompute
  51. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  52. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  53. 2026-08-14 02:57 UTCEG score recompute
  54. 2026-08-13 22:00 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  55. 2026-08-12 16:30 UTCEG score recompute
  56. 2026-08-12 13:51 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  57. 2026-08-11 15:46 UTCEG score recompute
  58. 2026-08-11 13:43 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  59. 2026-08-11 01:10 UTCEG score recompute
  60. 2026-08-11 00:00 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  61. 2026-08-10 00:09 UTCEG score recompute
  62. 2026-08-09 13:46 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  63. 2026-08-09 02:15 UTCEG score recompute
  64. 2026-08-08 16:37 UTCEPSS rescoreEPSS 0.5% · 43rd percentile
  65. 2026-08-07 19:06 UTCEG score recompute
  66. 2026-08-06 19:51 UTCEG score recompute
  67. 2026-08-06 13:46 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  68. 2026-08-05 21:57 UTCEG score recompute
  69. 2026-08-05 19:17 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  70. 2026-08-04 15:10 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  71. 2026-08-04 10:38 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  72. 2026-08-03 19:26 UTCEG score recompute
  73. 2026-08-03 10:36 UTCEPSS rescoreEPSS 0.5% · 42nd percentile
  74. 2026-08-02 13:02 UTCEG score recompute
  75. 2026-08-02 02:27 UTCEPSS rescoreEPSS 0.5% · 42nd percentile

Related CVEs(same product + same CWE)

Same product

1 shown

Debian:12:neatvnc

Frequently asked(5)

What is CVE-2026-42859?
CVE-2026-42859 is a high-severity vulnerability; its CVE record was published on May 11, 2026. Neat VNC is a VNC server library. Prior to 0.9.6, a pre-authentication stack buffer overflow exists in neatvnc in the RSA-AES security type handler. An unauthenticated remote attacker who can reach the VNC listening socket can send a crafted security type 5 (RSA-AES) or security type 129…
When was the CVE record for CVE-2026-42859 published?
The CVE record for CVE-2026-42859 was published on May 11, 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 October 26, 2026; the record at its source may have been updated since.
Is CVE-2026-42859 actively exploited?
CVE-2026-42859 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (50th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-42859?
CVE-2026-42859 has a CVSS v3 base score of 8.1 (NVD).
How do I remediate CVE-2026-42859?
A fix for CVE-2026-42859 is available: update to the fixed version the vendor names in its advisory.

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