CVE-2026-46678

MEDIUMPre-NVD 6.86.8
EchelonGraph scoreLOW confidence

This medium-severity CVE scores 6.8 under the CNA's CVSS (NVD's own analysis pending). EPSS exploit probability: 0.0%, top 88% 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: cna:github_m, epss
6.8
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 6.8Exploit: NoneExposed: 0

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

Pydantic AI: SSRF cloud-metadata blocklist bypass via IPv4-mapped IPv6 (Incomplete fix of CVE-2026-25580)

Summary

When an application using Pydantic AI opts a URL into force_download='allow-local' (which disables the default block on private/internal IPs), the cloud-metadata blocklist could be bypassed by encoding the metadata IP in an IPv6 transition form (IPv4-mapped IPv6, 6to4, or NAT64). Dual-stack and translated networks route the IPv6 wrapper to the underlying IPv4 endpoint, exposing cloud IAM short-term credentials.

This is an incomplete fix of GHSA-2jrp-274c-jhv3 / CVE-2026-25580. The parent advisory's remediation guaranteed that "cloud metadata endpoints are always blocked, even with allow-local." That guarantee did not hold for IPv6-encoded forms of the metadata IPs.

Severity

Same impact metrics as the parent CVE, but materially narrower attack surface (AC:H instead of AC:L), because exploitation requires the application to have opted into allow-local on a URL influenced by untrusted input.

Who Is Affected

Applications are affected only if they explicitly opt for FileUrl (ImageUrl, AudioUrl, VideoUrl, DocumentUrl) into force_download='allow-local' on a URL that is, or could be, influenced by untrusted input.

Applications are not affected if they use any of the bundled integrations to ingest user input, because they do not propagate force_download from external data:

  • Agent.to_web / clai web
  • VercelAIAdapter
  • AGUIAdapter / Agent.to_ag_ui

Applications that only download from developer-controlled URLs are not affected.

Remediation

Upgrade to 1.99.0 or later. The cloud-metadata and private-IP blocklists now apply to IPv6 transition forms that route to a blocked IPv4 endpoint (IPv4-mapped IPv6, 6to4, and NAT64 well-known prefix). The blocklists have also been extended to cover additional IANA-reserved IPv4 and IPv6 special-purpose ranges.

Workaround for Unpatched Versions

Avoid passing force_download='allow-local' on any URL that could be influenced by untrusted input. If developers must, resolve the hostname themselves and validate the result against their own metadata blocklist — including IPv6-encoded forms — before constructing the FileUrl.

Credits

Reported by j0hndo.

CVSS v3
6.8
EG Score
6.8(low)
EG Risk
35(Track)
EG Risk 35/100SSVC: 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
Severity68% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
12.2%
KEV
Not listed

Published

May 21, 2026

Last Modified

May 21, 2026

Vendor Advisories for CVE-2026-46678(1)

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

Affected Packages

(2 across 1 ecosystem)
PyPI(2)
PackageVulnerable rangeFixed inDependents
pydantic-ai1.56.0 ... 1.98.0 (49 versions)1.99.0—
pydantic-ai-slim1.56.0 ... 1.98.0 (49 versions)1.99.0—

Data Freshness Timeline

(refreshed 1× in last 7d / 1× 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. 2026-07-23 03:17 UTCEG score recompute
  2. 2026-06-14 23:18 UTCEPSS rescore
  3. 2026-06-13 23:00 UTCEPSS rescore
  4. 2026-06-12 23:12 UTCEPSS rescore
  5. 2026-05-24 06:09 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-46678?
CVE-2026-46678 is a medium vulnerability published on May 21, 2026. Pydantic AI: SSRF cloud-metadata blocklist bypass via IPv4-mapped IPv6 (Incomplete fix of CVE-2026-25580) Summary When an application using Pydantic AI opts a URL into force_download='allow-local' (which disables the default block on private/internal IPs), the cloud-metadata blocklist could be…
When was CVE-2026-46678 disclosed?
CVE-2026-46678 was first published in the National Vulnerability Database on May 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-46678 actively exploited?
CVE-2026-46678 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 12.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-46678?
CVE-2026-46678 has a CVSS v4.0 base score of 6.8 (CNA self-assessment; NVD's own analysis pending). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-46678?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-46678, 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

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