CVE-2026-42375

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-05-04. NVD baseline CVSS 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Elevated
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.8Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

D-Link DIR-600L Hardware Revision A1 (End-of-Life) contains a hardcoded telnet backdoor. The device starts a telnet daemon at boot via /bin/telnetd.sh with the username "Alphanetworks" and the static password "wrgn35_dlwbr_dir600l" read from /etc/alpha_config/image_sign. The custom telnetd binary accepts a -u user:password flag, and the custom login binary uses strcmp() to validate credentials. Successful authentication grants an unauthenticated attacker on the local network a root shell with full administrative control. The device has reached End-of-Life (EOL) and will not receive patches.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
60(Track*)
EG Risk 60/100SSVC: Track*

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
Severity98% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Watch closely — could escalate to Attend.
EPSS
38.2%
KEV
Not listed

Published

May 4, 2026

Last Modified

May 6, 2026

Advisory Details (1)

Auto-updated May 9, 2026
🔬 Proof of concept available. No patch confirmed yet.
generic🟡 PoC Available

CVE-2026-42375: Hardcoded Telnet Backdoor in D-Link DIR-600L A1 (End-of-Life) | Securin

https://www.securin.io/zero-day/cve-2026-42375-hardcoded-telnet-backdoor-in-d-link-dir-600l-a1-end-of-life-

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 33× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. 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. Most recent first.

Showing the most recent 100 of 160 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-42375?
CVE-2026-42375 is a critical vulnerability published on May 4, 2026. D-Link DIR-600L Hardware Revision A1 (End-of-Life) contains a hardcoded telnet backdoor. The device starts a telnet daemon at boot via /bin/telnetd.sh with the username "Alphanetworks" and the static password "wrgn35dlwbrdir600l" read from /etc/alphaconfig/imagesign. The custom telnetd binary…
When was CVE-2026-42375 disclosed?
CVE-2026-42375 was first published in the National Vulnerability Database on May 4, 2026, with the most recent update on May 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-42375 actively exploited?
CVE-2026-42375 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 38.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-42375?
CVE-2026-42375 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-42375?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-42375, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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