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CVE Record

CVE-2026-6734: undici vulnerable to cross-origin request routing via SOCKS5 proxy pool reuse

Impact: When using Socks5ProxyAgent, undici reuses a single connection pool across different origins without verifying that the pool's origin matches the requested origin. All requests are dispatched through the pool connected to the first origin, regardless of the intended destination. This causes cross-origin request routing: credentials and request data intended for origin B are sent to origin A, responses from the wrong origin are trusted, and HTTPS requests may be silently downgraded to HTTP. Impacted users are applications that use Socks5ProxyAgent (directly or via setGlobalDispatcher) and make requests to more than one origin. This was introduced in undici 7.23.0 via PR #4385 and affects all versions through 8.1.0. Patches: Upgrade to undici v7.26.0 or v8.2.0. Workarounds: Use a separate Socks5ProxyAgent instance per origin, or avoid using Socks5ProxyAgent with multiple origins.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Undici can send web requests to the wrong destination when a SOCKS5 proxy agent is reused across multiple sites. That can expose credentials or request data to the first origin and make the application trust the wrong response. The issue matters most for backend services using undici with SOCKS5 proxies and multiple destinations.

Executive priority

Prioritize remediation for services using SOCKS5 proxies to call multiple external or internal origins, especially where credentials or sensitive request bodies are present. Lower urgency applies where undici is absent, SOCKS5 is unused, or each origin already has a separate agent.

Technical view

Socks5ProxyAgent reuses one connection pool across origins without confirming the pool origin matches the requested origin. Requests for later origins are dispatched through the pool connected to the first origin, causing cross-origin routing, possible credential and data disclosure, response integrity loss, and silent HTTPS-to-HTTP downgrade.

Likely exposure

Exposure is limited to applications using undici Socks5ProxyAgent directly or via setGlobalDispatcher, and making requests to more than one origin. Affected undici versions are described as 7.23.0 through 8.1.0, with fixes in 7.26.0 and 8.2.0.

Exploitation context

The bundle does not show CISA KEV listing or active exploitation. Abuse depends on the vulnerable proxy-agent pattern existing in an application. CVSS 3.1 is 7.5 high with high confidentiality, integrity, and availability impact, but high attack complexity.

Researcher notes

Key conditions are version range, Socks5ProxyAgent use, and multi-origin request flow. The advisory maps to CWE-346 and CWE-940. Evidence names PR #4385 as the introduction point. Do not assume broader Node.js exposure without confirming this dependency and configuration.

Mitigation direction

  • Upgrade undici to 7.26.0 or 8.2.0.
  • Use a separate Socks5ProxyAgent instance per origin.
  • Avoid using Socks5ProxyAgent with multiple origins until upgraded.
  • Check Red Hat advisories for packaged dependency remediation.
  • Assess credential rotation if validation confirms cross-origin leakage.

Validation and detection

  • Inventory deployed undici versions in application dependencies and lockfiles.
  • Review code for Socks5ProxyAgent and setGlobalDispatcher usage.
  • Confirm whether one SOCKS5 agent handles multiple request origins.
  • Verify production builds use fixed undici versions.
  • Review logs for unexpected origin routing or response mismatches.
Prepared
Confidence
high
Sources
8

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-346: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-940: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-6734 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
2ADP providers
16Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: total

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H1.65.9openjs
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H1.65.9redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-6734Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPundici: undici: Information disclosure and data integrity issues due to incorrect Socks5ProxyAgent connection routing
other:Red Hat severity ratingcvssV3_1
  • 2026-06-17T19:04:00.272Z: Reported to Red Hat.
  • 2026-06-17T16:36:55.439Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
undiciundici7.23.0, 7.26.0, 8.0.0, 8.2.0unaffected
Weakness

CWE details

CWE-346CWE-940

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-346 · source CWE mapping

Origin Validation Error

Origin Validation Error represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-940 · source CWE mapping

Improper Verification of Source of a Communication Channel

Improper Verification of Source of a Communication Channel represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs