How severe is CVE-2026-6734?

CVE-2026-6734 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-6734 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-6734?

CVE-2026-6734 affects Nodejs Undici. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-6734?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-6734 have an EU (EUVD) identifier?

Yes. CVE-2026-6734 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-37760.

When was CVE-2026-6734 published?

CVE-2026-6734 was published on 2026-06-17 and last updated on 2026-07-07.

CVE-2026-6734

CVE-2026-6734 is a high-severity vulnerability in Nodejs Undici with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-346.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (24th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-37760
Weakness: CWE-346
Affected product: Nodejs Undici
Published: 2026-06-17
Last modified: 2026-07-07

Description

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.

Frequently asked questions

What is CVE-2026-6734?: 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.
How severe is CVE-2026-6734?: CVE-2026-6734 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-6734 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-6734?: CVE-2026-6734 affects Nodejs Undici. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-6734?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-6734 have an EU (EUVD) identifier?: Yes. CVE-2026-6734 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-37760.
When was CVE-2026-6734 published?: CVE-2026-6734 was published on 2026-06-17 and last updated on 2026-07-07.

References

Affected products (1)

cpe:2.3:a:nodejs:undici:*:*:*:*:*:node.js:*:*

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