CVE-2026-40518

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.1 under NVD CVSS v3. EPSS exploit probability: 0.4%, top 71% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
Elevated
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.1Exploit: Elevated riskExposed: 0

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

ByteDance DeerFlow before commit 2176b2b contains a path traversal and arbitrary file write vulnerability in bootstrap-mode custom-agent creation where the agent name validation is bypassed. Attackers can supply traversal-style values or absolute paths as the agent name to influence directory creation and write files outside the intended custom-agent directory, potentially achieving arbitrary file write on the system subject to filesystem permissions.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
57(Track)
EG Risk 57/100SSVC: 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
Severity91% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
29%
KEV
Not listed

Published

April 17, 2026

Last Modified

August 14, 2026

Advisory Details (3)

Auto-updated Sep 7, 2026
Patch available. Sources: github_pr, github_commit.
generic

ByteDance DeerFlow Path Traversal and Arbitrary File Write via Bootstrap Mode | Advisories | VulnCheck

https://www.vulncheck.com/advisories/bytedance-deerflow-path-traversal-and-arbitrary-file-write-via-bootstrap-mode
github_commit Patch Available

commit 2176b2bbfccf (bytedance/deer-flow)

Patch available: bytedance/deer-flow v2.0.0 (contains commit 2176b2bbfccf)

https://github.com/bytedance/deer-flow/commit/2176b2bbfccfce25ceee08318813f96d843a13fd
github_pr Patch Available

fix: validate bootstrap agent names before filesystem writes

Patch available: bytedance/deer-flow v2.0.0 (PR #2274 merged 2026-04-16)

https://github.com/bytedance/deer-flow/pull/2274

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 28× 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 223 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-40518?
CVE-2026-40518 is a critical vulnerability published on April 17, 2026. ByteDance DeerFlow before commit 2176b2b contains a path traversal and arbitrary file write vulnerability in bootstrap-mode custom-agent creation where the agent name validation is bypassed. Attackers can supply traversal-style values or absolute paths as the agent name to influence directory…
When was CVE-2026-40518 disclosed?
CVE-2026-40518 was first published in the National Vulnerability Database on April 17, 2026, with the most recent update on August 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40518 actively exploited?
CVE-2026-40518 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 71.0% of all scored CVEs.
What is the CVSS score of CVE-2026-40518?
CVE-2026-40518 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-40518?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40518, 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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