CVE-2026-49857

HIGHPre-NVD 7.47.4
EchelonGraph scoreMEDIUM confidence

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

This high-severity CVE scores 7.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5% (41st 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

Also known asEUVD-2026-58054 (ENISA EUVD) · GHSA-pvrj-8cg3-j5f8 (GitHub Security Advisories)Source: ENISA EUVD

7.4EG
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: 0.5%CVSS: 7.4Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

auth-fetch-mcp is an MCP server that lets AI assistants fetch content from authenticated web pages. Version 3.0.1 implements SSRF protection in assertSafeUrl() (src/security.ts) to block requests to private and loopback addresses. However, the isPrivateV6() function fails to detect IPv4-mapped IPv6 loopback addresses in their hex-normalized form. When an attacker supplies a URL such as http://[::ffff:127.0.0.1]:PORT/, the Node.js WHATWG URL parser silently normalizes the host to [::ffff:7f00:1]. Because net.isIPv4('7f00:1') returns false, the private-IP check is bypassed and the URL is passed to the browser or HTTP client, allowing the MCP tool to reach loopback services that are supposed to be blocked. The issue is exploitable under default configuration without any special environment variable. Version 3.0.1 patches the issue.

CVSS v3
7.4
EG Score
7.4HIGHmedium confidence
EG Risk
33
EG Risk 33/100

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)
Severity74% × 45%
Impact severity (EG Severity): CVSS 7.4 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.5% × 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 every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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
0.5%
EPSS %ILE
41st
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 (7.4): severity, escalated by confirmed exploitation. This CVE's 7.4 is its impact severity (EG Severity), not escalated.

EG Severity
7.4 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.a secondary CVSS source · CVSS v3.0 or v3.1
EG Likelihood
0.5% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-24). 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 every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade 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 every mission impact level.

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

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (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)60 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 partial (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

July 1, 2026

Last Modified

October 24, 2026

Advisory Details (3)

Auto-updated Aug 13, 2026
Patch available. Sources: github, github_commit, github_release.
GitHub release Patch Available

v3.0.1

Patch available: ymw0407/auth-fetch-mcp v3.0.1

https://github.com/ymw0407/auth-fetch-mcp/releases/tag/v3.0.1
GitHub commit Patch Available

commit c5c523cd55b2 (ymw0407/auth-fetch-mcp)

Patch available: ymw0407/auth-fetch-mcp v3.0.1 (contains commit c5c523cd55b2)

https://github.com/ymw0407/auth-fetch-mcp/commit/c5c523cd55b24ae1680c5bacef95d59a81ae3450
GitHub advisoryMentions a patch (unverified)

SSRF Protection Bypass via IPv4-mapped IPv6 Loopback · Advisory · ymw0407/auth-fetch-mcp · GitHub

https://github.com/ymw0407/auth-fetch-mcp/security/advisories/GHSA-pvrj-8cg3-j5f8

Vendor Advisories for CVE-2026-49857(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
auth-fetch-mcp—
  • every version up to 3.0.2: fixed in 3.0.2
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 37× 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. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  2. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  3. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  4. 2026-10-25 14:22 UTCEG score recompute
  5. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  6. 2026-10-23 18:26 UTCEG score recompute
  7. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  8. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  9. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.5% · 41st percentile
  10. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  11. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  12. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  13. 2026-10-18 03:34 UTCEG score recompute
  14. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  15. 2026-10-17 11:53 UTCEG score recompute
  16. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  17. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  18. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  19. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  20. 2026-10-13 16:24 UTCOSV refresh
  21. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  22. 2026-10-12 15:59 UTCEG score recompute
  23. 2026-10-11 19:43 UTCEG score recompute
  24. 2026-10-11 16:57 UTCEG score recompute
  25. 2026-10-11 14:21 UTCEG score recompute
Show 73 more
  1. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  2. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  3. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  4. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  5. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.5% · 40th percentile
  6. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  7. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  8. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  9. 2026-10-03 14:25 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  10. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  11. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  12. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  13. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  14. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  15. 2026-09-26 00:27 UTCEPSS rescoreEPSS 0.5% · 39th percentile
  16. 2026-09-23 17:53 UTCEPSS rescoreEPSS 0.3% · 28th percentile
  17. 2026-09-23 06:51 UTCEG score recompute
  18. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 28th percentile
  19. 2026-09-18 20:36 UTCEG score recompute
  20. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 28th percentile
  21. 2026-09-18 06:32 UTCEG score recompute
  22. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 28th percentile
  23. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  24. 2026-09-14 00:23 UTCEG score recompute
  25. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  26. 2026-09-13 09:08 UTCEG score recompute
  27. 2026-09-12 14:42 UTCEG score recompute
  28. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  29. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  30. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  31. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  32. 2026-09-06 14:27 UTCEG score recompute
  33. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  34. 2026-09-06 02:20 UTCEG score recompute
  35. 2026-09-04 05:06 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  36. 2026-09-02 14:12 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  37. 2026-09-01 13:54 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  38. 2026-09-01 04:40 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  39. 2026-08-30 22:40 UTCEG score recompute
  40. 2026-08-30 19:17 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  41. 2026-08-30 11:46 UTCEG score recompute
  42. 2026-08-30 01:22 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  43. 2026-08-28 21:41 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  44. 2026-08-27 22:26 UTCEG score recompute
  45. 2026-08-27 14:25 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  46. 2026-08-26 14:46 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  47. 2026-08-25 13:49 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  48. 2026-08-24 21:02 UTCEG score recompute
  49. 2026-08-23 06:52 UTCEG score recompute
  50. 2026-08-23 00:19 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  51. 2026-08-22 07:10 UTCEG score recompute
  52. 2026-08-21 23:49 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  53. 2026-08-21 04:32 UTCEG score recompute
  54. 2026-08-20 22:55 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  55. 2026-08-20 04:41 UTCEG score recompute
  56. 2026-08-19 17:04 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  57. 2026-08-18 20:59 UTCEG score recompute
  58. 2026-08-18 13:48 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  59. 2026-08-17 23:26 UTCEG score recompute
  60. 2026-08-17 13:47 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  61. 2026-08-16 22:31 UTCEG score recompute
  62. 2026-08-16 14:56 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  63. 2026-08-16 11:37 UTCEG score recompute
  64. 2026-08-16 02:14 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  65. 2026-08-15 02:59 UTCEG score recompute
  66. 2026-08-15 01:30 UTCEPSS rescoreEPSS 0.3% · 27th percentile
  67. 2026-08-13 18:19 UTCEG score recompute
  68. 2026-08-13 18:12 UTCEG score recompute
  69. 2026-08-13 15:28 UTCEG score recompute
  70. 2026-07-30 10:06 UTCEG score recompute
  71. 2026-07-26 13:16 UTCEG score recompute
  72. 2026-07-23 03:18 UTCEG score recompute
  73. 2026-07-01 19:05 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-49857?
CVE-2026-49857 is a high-severity vulnerability; its CVE record was published on July 1, 2026. auth-fetch-mcp is an MCP server that lets AI assistants fetch content from authenticated web pages. Version 3.0.1 implements SSRF protection in assertSafeUrl() (src/security.ts) to block requests to private and loopback addresses. However, the isPrivateV6() function fails to detect IPv4-mapped IPv6…
When was the CVE record for CVE-2026-49857 published?
The CVE record for CVE-2026-49857 was published on July 1, 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 24, 2026; the record at its source may have been updated since.
Is CVE-2026-49857 actively exploited?
CVE-2026-49857 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.5% probability of exploitation in the next 30 days (41st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-49857?
CVE-2026-49857 has a CVSS base score of 7.4 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-49857?
A fix for CVE-2026-49857 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-49857 are linked in the Vendor Advisories panel on this page.

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