CVE-2026-55557

HIGHPre-NVD 8.68.6—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.6 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 91% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this week
8.6EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 8.6Exploit: None knownExposed: 0

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

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
8.6(medium)
EG Risk
39(Track)
EG Risk 39/100SSVC: 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
Severity86% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
9%
KEV
Not listed

Published

August 25, 2026

Last Modified

August 25, 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
generic

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_pr 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 Patch Available

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 rangeFixed inDependents
browse-mcp—0.8.2—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 12× 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.

  1. 2026-08-30 01:22 UTCEPSS rescore
  2. 2026-08-29 06:39 UTCEG score recompute
  3. 2026-08-28 21:41 UTCEPSS rescore
  4. 2026-08-27 18:50 UTCEG score recompute
  5. 2026-08-27 14:25 UTCEPSS rescore
  6. 2026-08-26 19:04 UTCEG score recompute
  7. 2026-08-26 14:46 UTCEPSS rescore
  8. 2026-08-25 19:20 UTCEG score recompute
  9. 2026-08-25 19:10 UTCEG score recompute
  10. 2026-08-25 17:24 UTCEG score recompute
  11. 2026-08-25 16:40 UTCEG score recompute
  12. 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 vulnerability 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 CVE-2026-55557 disclosed?
CVE-2026-55557 was first published in the National Vulnerability Database on August 25, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55557 actively exploited?
CVE-2026-55557 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 91.5% of all scored CVEs.
What is the CVSS score of CVE-2026-55557?
CVE-2026-55557 has a CVSS v3 base score of 8.6 (NVD).
How do I remediate CVE-2026-55557?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55557, 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.

Dependency Blast Radius

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

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