CVE-2026-55557

HIGHPre-NVD 8.68.6
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 8.6 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2% (13th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from a secondary CVSS source
Sources: EPSS, a secondary CVSS source
8.6EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.2%CVSS: 8.6Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

browse-mcp is a Playwright-based headless-browser MCP server for MCP-capable agents. Prior to 0.8.2, browser_download writes a fetched response body to join(save_dir, filename) without validating the caller-controlled save_dir, while browser_save_state and browser_load_state honor a caller-controlled path unchanged. A malicious MCP client, or an autonomous agent steered by indirect prompt injection on a visited page, can choose an arbitrary save_dir or state path and a URL whose response body becomes attacker-controlled file contents, allowing writes to any path the process can reach, including ~/.bashrc, autostart entries, or cron files, and potentially leading to host code execution. The force_fetch fallback also uses a raw fetch() that bypasses the BROWSE_MCP_ALLOWED_ORIGINS origin fence. This issue is fixed in version 0.8.2.

CVSS v3
8.6
EG Score
8.6HIGHmedium confidence
EG Risk
39
EG Risk 39/100

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)
Severity86% × 45%
The EG Score, 8.6 of 10.
Exploitation0.2% × 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 low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (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.
EPSS PROB
0.2%
EPSS %ILE
13th
KEV
Not listed

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (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)14 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 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

August 25, 2026

Last Modified

September 9, 2026

Advisory Details (5)

Auto-updated Aug 25, 2026
Patch available. Sources: github_pr, github_commit, github_release, github.
GitHub release Patch Available

v0.8.2 — path confinement (CWE-22) security fix

Patch available: That1Drifter/browse-mcp v0.8.2

https://github.com/That1Drifter/browse-mcp/releases/tag/v0.8.2
Web page

browse-mcp/CHANGELOG.md at v0.8.2 · That1Drifter/browse-mcp · GitHub

https://github.com/That1Drifter/browse-mcp/blob/v0.8.2/CHANGELOG.md#082---2026-06-13
GitHub commit Patch Available

commit 5352a4a56f62 (That1Drifter/browse-mcp)

Patch available: That1Drifter/browse-mcp v0.8.2 (contains commit 5352a4a56f62)

https://github.com/That1Drifter/browse-mcp/commit/5352a4a56f626254b445bfa07e4bb48c5aad15c1
GitHub pull request Patch Available

fix(security): confine download/state write paths to data roots (CWE-22)

Patch available: That1Drifter/browse-mcp v0.8.2 (PR #58 merged 2026-06-13)

https://github.com/That1Drifter/browse-mcp/pull/58
GitHub advisoryMentions a patch (unverified)

Arbitrary file write via unconfined download and state paths (CWE-22) · Advisory · That1Drifter/browse-mcp · GitHub

Affected: 0.8.2.

https://github.com/That1Drifter/browse-mcp/security/advisories/GHSA-m9mq-7m7q-xc6p

Vendor Advisories for CVE-2026-55557(1)

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

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFix by version rangeDependents
browse-mcp—
  • every version up to 0.8.2: fixed in 0.8.2
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 14× in last 7d / 55× 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.

  1. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  2. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  3. 2026-10-12 15:55 UTCEG score recompute
  4. 2026-10-11 19:39 UTCEG score recompute
  5. 2026-10-11 16:54 UTCEG score recompute
  6. 2026-10-11 14:17 UTCEG score recompute
  7. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  8. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  9. 2026-10-10 12:00 UTCEG score recompute
  10. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  11. 2026-10-09 04:21 UTCEG score recompute
  12. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  13. 2026-10-08 03:14 UTCEG score recompute
  14. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  15. 2026-10-06 19:44 UTCEG score recompute
  16. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  17. 2026-10-06 07:42 UTCEG score recompute
  18. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  19. 2026-10-05 04:42 UTCEG score recompute
  20. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  21. 2026-10-03 16:26 UTCEG score recompute
  22. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  23. 2026-10-02 19:51 UTCEG score recompute
  24. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  25. 2026-10-01 20:03 UTCEG score recompute
Show 66 more
  1. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  2. 2026-09-30 20:14 UTCEG score recompute
  3. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  4. 2026-09-30 06:45 UTCEG score recompute
  5. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  6. 2026-09-28 22:24 UTCEG score recompute
  7. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  8. 2026-09-27 22:21 UTCEG score recompute
  9. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  10. 2026-09-26 22:02 UTCEG score recompute
  11. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  12. 2026-09-24 22:15 UTCEG score recompute
  13. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.2% · 13th percentile
  14. 2026-09-23 20:56 UTCEG score recompute
  15. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  16. 2026-09-22 21:13 UTCEG score recompute
  17. 2026-09-21 21:30 UTCEG score recompute
  18. 2026-09-20 21:43 UTCEG score recompute
  19. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  20. 2026-09-19 21:59 UTCEG score recompute
  21. 2026-09-18 21:34 UTCEG score recompute
  22. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  23. 2026-09-17 21:08 UTCEG score recompute
  24. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  25. 2026-09-16 19:29 UTCEG score recompute
  26. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  27. 2026-09-16 07:37 UTCEG score recompute
  28. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  29. 2026-09-15 07:53 UTCEG score recompute
  30. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  31. 2026-09-13 20:16 UTCEG score recompute
  32. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  33. 2026-09-12 20:33 UTCEG score recompute
  34. 2026-09-11 20:49 UTCEG score recompute
  35. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  36. 2026-09-10 21:00 UTCEG score recompute
  37. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  38. 2026-09-09 01:13 UTCEG score recompute
  39. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  40. 2026-09-07 20:00 UTCEG score recompute
  41. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  42. 2026-09-06 20:16 UTCEG score recompute
  43. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  44. 2026-09-05 20:32 UTCEG score recompute
  45. 2026-09-04 20:49 UTCEG score recompute
  46. 2026-09-04 08:20 UTCEG score recompute
  47. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  48. 2026-09-02 20:43 UTCEG score recompute
  49. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  50. 2026-09-01 17:53 UTCEG score recompute
  51. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  52. 2026-08-31 06:14 UTCEG score recompute
  53. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  54. 2026-08-30 06:27 UTCEG score recompute
  55. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  56. 2026-08-29 06:39 UTCEG score recompute
  57. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  58. 2026-08-27 18:50 UTCEG score recompute
  59. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  60. 2026-08-26 19:04 UTCEG score recompute
  61. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.2% · 8th percentile
  62. 2026-08-25 19:20 UTCEG score recompute
  63. 2026-08-25 19:10 UTCEG score recompute
  64. 2026-08-25 17:24 UTCEG score recompute
  65. 2026-08-25 16:40 UTCEG score recomputeFirst assessed: 8.6 HIGH
  66. 2026-08-25 16:40 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-55557?
CVE-2026-55557 is a high-severity vulnerability; its CVE record was published on August 25, 2026. browse-mcp is a Playwright-based headless-browser MCP server for MCP-capable agents. Prior to 0.8.2, browserdownload writes a fetched response body to join(savedir, filename) without validating the caller-controlled savedir, while browsersavestate and browserloadstate honor a caller-controlled path…
When was the CVE record for CVE-2026-55557 published?
The CVE record for CVE-2026-55557 was published on August 25, 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-2026-55557 actively exploited?
CVE-2026-55557 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.2% probability of exploitation in the next 30 days (13th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55557?
CVE-2026-55557 has a CVSS base score of 8.6 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-55557?
A fix for CVE-2026-55557 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55557 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-55557

Explore →

Is Your Infrastructure Affected by CVE-2026-55557?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs