CVE-2026-80347

HIGHPre-NVD 7.57.5
EchelonGraph scoreHIGH confidence

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

Score 7.5 from GitHub Security Advisory (severity: HIGH) published 2026-09-24. A secondary CVSS source baseline 7.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 3 sources updated this weekElevated
7.5EG
EchelonGraph verdictPlan mitigationRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 7.5Exploit: No code on recordExposed services: Not assessed

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

The CVE record's CNA (VulnCheck) lists kazuph mcp-fetch versions up to and including 1.6.3 as affected. No release containing a fix is confirmed on record.

mcp-fetch checks a fetch target against its SSRF guard without removing the brackets that surround an IPv6 literal. isSafeUrl reads the hostname from the parsed URL, which for a literal such as http://[::1]/ yields the bracketed string, and then tests it with net.isIP. That call returns zero for a bracketed value, so the branch holding the private-address checks is skipped entirely. The guard falls back to resolving the hostname, the bracketed string is not a resolvable name, no addresses are returned, and the target is reported safe. The HTTP client then strips the brackets and connects. Because the address may be given in IPv4-mapped form, the same path reaches any IPv4 target the loopback and private checks were meant to exclude, including link-local metadata endpoints. isPrivateIPv6 also has no case for the ::ffff: prefix, so the mapped form would still pass even if the brackets were removed. The fetch target is supplied as a tool argument, so an attacker who can influence what the model requests can read internal responses back into the model context.

CVSS v3
7.5
EG Score
7.5HIGHhigh confidence
EG Risk
65
EG Risk 65/100

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)
Severity75% × 45%
The EG Score, 7.5 of 10.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable yes (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: No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.
EPSS PROB
0.4%
EPSS %ILE
26th
KEV
Not listed

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

No fix is confirmed yet. Restrict network exposure of the affected system or apply the vendor's mitigation within your standard update timelines at low or medium mission impact and sooner than that at high, and watch the vendor's advisory for the fix.

Exploitation public PoC (CISA Vulnrichment) · Automatable yes (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)14 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (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

August 26, 2026

Last Modified

September 24, 2026

Advisory Details (3)

Auto-updated Aug 26, 2026
No fix on record yet.
Web page

mcp-fetch through 1.6.3 Server-Side Request Forgery via Unstripped IPv6 Literal Brackets | Advisories | VulnCheck

https://www.vulncheck.com/advisories/mcp-fetch-through-1.6.3-server-side-request-forgery-via-unstripped-ipv6-literal-brackets
Web page

SSRF guard bypass via IPv6 literal (brackets not stripped before net.isIP) · Issue #16 · kazuph/mcp-fetch · GitHub

https://github.com/kazuph/mcp-fetch/issues/16
Web page

GitHub - kazuph/mcp-fetch · GitHub

https://github.com/kazuph/mcp-fetch

Vendor Advisories for CVE-2026-80347(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 19× in last 7d / 82× 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.

Showing the most recent 98 of 117 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 2 repeat rows among the latest 100 are merged into the row they repeat. The 19 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-13 16:35 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  2. 2026-10-13 06:30 UTCEG score recompute
  3. 2026-10-13 06:30 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  4. 2026-10-12 16:35 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  5. 2026-10-12 14:57 UTCEG score recompute
  6. 2026-10-11 19:21 UTCEG score recompute
  7. 2026-10-11 16:37 UTCEG score recompute
  8. 2026-10-11 13:56 UTCEG score recompute
  9. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  10. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  11. 2026-10-10 06:49 UTCEG score recompute
  12. 2026-10-10 06:49 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  13. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  14. 2026-10-09 03:29 UTCEG score recompute
  15. 2026-10-09 03:28 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  16. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  17. 2026-10-08 01:59 UTCEG score recompute
  18. 2026-10-08 01:59 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  19. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  20. 2026-10-07 07:59 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  21. 2026-10-06 19:47 UTCEG score recompute
  22. 2026-10-06 19:47 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  23. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  24. 2026-10-06 07:37 UTCEG score recompute
  25. 2026-10-06 07:37 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
Show 73 more
  1. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  2. 2026-10-05 16:58 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  3. 2026-10-05 04:47 UTCEG score recompute
  4. 2026-10-05 04:47 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  5. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  6. 2026-10-04 16:35 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  7. 2026-10-04 04:23 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  8. 2026-10-03 16:13 UTCEG score recompute
  9. 2026-10-03 16:13 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  10. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  11. 2026-10-02 21:31 UTCEG score recompute
  12. 2026-10-02 21:31 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  13. 2026-10-02 17:57 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  14. 2026-10-02 09:08 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  15. 2026-10-01 20:46 UTCEG score recompute
  16. 2026-10-01 20:46 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  17. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  18. 2026-10-01 08:11 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  19. 2026-09-30 20:00 UTCEG score recompute
  20. 2026-09-30 20:00 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  21. 2026-09-30 15:04 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  22. 2026-09-30 06:11 UTCEG score recompute
  23. 2026-09-30 06:11 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  24. 2026-09-29 12:34 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  25. 2026-09-28 22:03 UTCEG score recompute
  26. 2026-09-28 22:03 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  27. 2026-09-28 13:52 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  28. 2026-09-28 09:51 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  29. 2026-09-27 21:40 UTCEG score recompute
  30. 2026-09-27 21:40 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  31. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  32. 2026-09-27 09:29 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  33. 2026-09-26 21:12 UTCEG score recompute
  34. 2026-09-26 21:12 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  35. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  36. 2026-09-26 00:28 UTCEPSS rescoreEPSS 0.4% · 26th percentile
  37. 2026-09-25 09:25 UTCEG score recompute
  38. 2026-09-25 09:25 UTCGHSA enrichmentGHSA-mqq2-4r9w-4h99 · GitHub severity HIGH · GitHub CVSS 7.5
  39. 2026-09-24 20:19 UTCEG score recompute
  40. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.5% · 38th percentile
  41. 2026-09-23 19:55 UTCEG score recompute
  42. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  43. 2026-09-22 18:47 UTCEG score recompute
  44. 2026-09-22 16:01 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  45. 2026-09-22 05:54 UTCEG score recompute
  46. 2026-09-21 21:09 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  47. 2026-09-21 05:31 UTCEG score recompute
  48. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  49. 2026-09-19 16:57 UTCEG score recompute
  50. 2026-09-19 04:43 UTCEG score recompute
  51. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  52. 2026-09-18 04:21 UTCEG score recompute
  53. 2026-09-16 15:46 UTCEG score recompute
  54. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  55. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  56. 2026-09-15 15:22 UTCEG score recompute
  57. 2026-09-15 03:12 UTCEPSS rescoreEPSS 0.3% · 20th percentile
  58. 2026-09-14 02:47 UTCEG score recompute
  59. 2026-09-13 02:25 UTCEG score recompute
  60. 2026-09-12 02:03 UTCEG score recompute
  61. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  62. 2026-09-10 13:28 UTCEG score recompute
  63. 2026-09-09 00:52 UTCEG score recompute
  64. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  65. 2026-09-07 22:51 UTCEG score recompute
  66. 2026-09-06 22:26 UTCEG score recompute
  67. 2026-09-06 13:48 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  68. 2026-09-05 21:55 UTCEG score recompute
  69. 2026-09-05 15:31 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  70. 2026-09-04 21:30 UTCEG score recompute
  71. 2026-09-04 09:14 UTCEG score recompute
  72. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.3% · 19th percentile
  73. 2026-09-02 20:35 UTCEG score recompute

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-80347?
CVE-2026-80347 is a high-severity vulnerability; its CVE record was published on August 26, 2026. mcp-fetch checks a fetch target against its SSRF guard without removing the brackets that surround an IPv6 literal. isSafeUrl reads the hostname from the parsed URL, which for a literal such as http://[::1]/ yields the bracketed string, and then tests it with net.isIP. That call returns zero for a…
When was CVE-2026-80347 made public?
CVE-2026-80347 was made public on August 26, 2026: that is the date its CVE record's CNA, VulnCheck, gives for when the vulnerability was made public. The CVE record itself was published on August 26, 2026. EchelonGraph's copy of the record carries a last-modified date of September 24, 2026; the record at its source may have been updated since.
Is CVE-2026-80347 actively exploited?
CVE-2026-80347 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (26th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-80347?
CVE-2026-80347 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-80347?
No fix for CVE-2026-80347 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix. The CVE record's CNA (VulnCheck) lists kazuph mcp-fetch versions up to and including 1.6.3 as affected. No release containing a fix is confirmed on record. The vendor advisories EchelonGraph has for CVE-2026-80347 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

Explore the affected products and dependency analysis for CVE-2026-80347

Explore →

Is Your Infrastructure Affected by CVE-2026-80347?

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

Book a Demo →Browse All CVEs