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Response snapshot Oct 31, 2026, 01:26 UTC

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VulnerabilityCVE-2026-116689

follow-redirects: Cross-realm sensitiveHeaders arrays are discarded and custom credentials can follow redirects

follow-redirects 1.16.0 and 1.16.1 validate the documented sensitiveHeaders option with instanceof Array.

At a glance

Exploited
Not known
Severity
8.2 High (CVSS 4.0)
Chance of exploitation
Not estimated
Sources
1 source

What to do

GitHub lists first patched versions: follow-redirects: 1.16.2. Confirm the affected range and upgrade guidance in the exact advisory.

Read GitHub-reviewed advisory GHSA-mrwp-f3q8-3g9p (opens a new tab)

What happened

Summary

follow-redirects 1.16.0 and 1.16.1 validate the documented sensitiveHeaders option with instanceof Array. An array created in another JavaScript realm is silently replaced with an empty list, so a caller-declared custom credential header can be forwarded to an attacker-controlled cross-origin redirect destination.

Details

Affected versions

Continue reading

The sensitiveHeaders option was introduced in 1.16.0. Published 1.16.0 and 1.16.1 both reproduced, giving a tested affected range of 1.16.0 through 1.16.1. The source checkout was pinned at revision 46301256333c90b7faac7aa126effe72ec16d16e; the exact npm 1.16.1 artifact reproduced independently.

Root cause

index.js resets options.sensitiveHeaders when its local isArray() helper returns false. That helper uses value instanceof Array, which depends on realm identity. The same file already uses Array.isArray(options.headers), which correctly recognizes arrays across realms.

Suggested remediation

Use Array.isArray(value) for sensitiveHeaders, then validate and normalize each member as a header-name string. Add same-realm and node:vm cross-realm tests for cross-origin redirects, including the array-form headers representation. Verify that custom sensitive names are removed while unrelated headers remain unchanged.

Duplicate review

The public advisory history contains other sensitive-header findings, including array-form headers and regular-expression handling, but focused repository searches found no report describing cross-realm validation as of 2026-10-25. A private or differently worded report may already exist.

Proof of concept

Start two loopback HTTP servers. The first returns a 302 redirect to the second. Send X-API-Key and list that name in sensitiveHeaders, then compare a normal array with a genuine cross-realm array created by:

const vm = require('node:vm');
const sensitiveHeaders = vm.runInNewContext(`['X-API-Key']`);

Observed against both source and the exact npm 1.16.1 package:

- Same-realm ['X-API-Key']: the redirect target did not receive the key. - Cross-realm ['X-API-Key']: Array.isArray(value) was true, value instanceof Array was false, and the redirect target received X-API-Key. - An unrelated X-Harmless header remained present in both cases.

The complete 3.5 KB loopback-only harness and raw JSON output are available privately.

Impact

custom credential disclosure. Exploitation requires a direct caller or wrapper that preserves a cross-realm sensitiveHeaders array, a custom credential listed in that option, and an attacker-controlled or compromised endpoint that returns a cross-origin redirect. The directly demonstrated result is disclosure of the custom header value, potentially exposing an API key or service token until revocation.

Built-in Authorization, Proxy-Authorization, and Cookie protections remained effective. Exact Axios 1.20.0 with follow-redirects 1.16.1 did not reproduce because Axios normalized the array; this report does not claim that Axios is affected. No third-party service was tested.

Affected package ranges reported by GitHub: follow-redirects: >= 1.16.0, <= 1.16.1

Scores and how they were measured

CVSS base severity

8.2

Version 4.0As of

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Related technology

Sources

  1. Primary source

    GitHub-reviewed advisory GHSA-mrwp-f3q8-3g9p (opens a new tab)

    The public advisory supplies the description, affected package/version ranges, and any listed CVSS metric. GitHub review is not local review.

    Published Checked

  2. Primary source

    GitHub public advisory API page (opens a new tab)

    The API page supplied GHSA-mrwp-f3q8-3g9p, its actual identifiers, source dates, and structured metrics.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 30). follow-redirects: Cross-realm sensitiveHeaders arrays are discarded and custom credentials can follow redirects (CVE-2026-116689). https://kevwire.com/record/CVE-2026-116689

MLA

"follow-redirects: Cross-realm sensitiveHeaders arrays are discarded and custom credentials can follow redirects (CVE-2026-116689)." KEVWire, 30 Oct. 2026, kevwire.com/record/CVE-2026-116689.

Chicago

KEVWire. "follow-redirects: Cross-realm sensitiveHeaders arrays are discarded and custom credentials can follow redirects (CVE-2026-116689)." Last modified October 30, 2026. https://kevwire.com/record/CVE-2026-116689.

Evidence summary (plain text)

follow-redirects: Cross-realm sensitiveHeaders arrays are discarded and custom credentials can follow redirects (Oct 30, 2026).
follow-redirects 1.16.0 and 1.16.1 validate the documented sensitiveHeaders option with instanceof Array. An array created in another JavaScript realm is silently replaced with an empty list, so a caller-declared custom credential header can be forwarded to an attacker-controlled cross-origin redirect destination.

Affected versions

The sensitiveHeaders option was introduced in 1.16.0. Published 1.16.0 and 1.16.1 both reproduced, giving a tested affected range of 1.16.0 through 1.16.1.
CVSS 8.2 (version 4.0; evidence as of Oct 30, 2026; https://github.com/advisories/GHSA-mrwp-f3q8-3g9p).
Sources:
GitHub-reviewed advisory GHSA-mrwp-f3q8-3g9p: https://github.com/advisories/GHSA-mrwp-f3q8-3g9p
GitHub public advisory API page: https://api.github.com/advisories?type=reviewed&per_page=100&sort=updated&direction=desc
Record ID: CVE-2026-116689.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 31, 2026, 00:50 UTC. Ingestion is not an independent editorial investigation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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