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CVE Record

CVE-2026-40895: follow-redirects: Custom Authentication Headers Leaked to Cross-Domain Redirect Targets

follow-redirects is an open source, drop-in replacement for Node's `http` and `https` modules that automatically follows redirects. Prior to 1.16.0, when an HTTP request follows a cross-domain redirect (301/302/307/308), follow-redirects only strips authorization, proxy-authorization, and cookie headers (matched by regex at index.js). Any custom authentication header (e.g., X-API-Key, X-Auth-Token, Api-Key, Token) is forwarded verbatim to the redirect target. This vulnerability is fixed in 1.16.0.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Applications using vulnerable follow-redirects can unintentionally send private custom authentication headers to a different domain after an HTTP redirect. This can expose API keys or tokens to a redirect target the application did not originally intend to trust.

Executive priority

Treat this as a high-priority dependency exposure issue for applications that use API keys or tokens in custom headers. Patch quickly where follow-redirects is present, especially in services calling third-party or user-controlled URLs.

Technical view

Before 1.16.0, follow-redirects stripped authorization, proxy-authorization, and cookie headers on cross-domain redirects, but forwarded custom authentication headers such as X-API-Key or X-Auth-Token. The issue affects follow-redirects versions below 1.16.0 and is fixed in 1.16.0.

Likely exposure

Exposure is most likely in Node.js applications or dependencies using follow-redirects below 1.16.0 while sending custom authentication headers to URLs that may redirect across domains.

Exploitation context

The supplied sources do not show KEV listing or active exploitation evidence. Abuse would require a request path where an application follows a cross-domain redirect while carrying sensitive custom headers.

Researcher notes

Key research question is whether the application can be induced to follow a cross-domain redirect while carrying non-standard secret headers. The public bundle names the fixed version but does not provide active exploitation evidence.

Mitigation direction

  • Upgrade follow-redirects to version 1.16.0 or later.
  • Review lockfiles for transitive follow-redirects versions below 1.16.0.
  • Check Red Hat advisories for affected packaged products and vendor-fixed builds.
  • Avoid sending custom secrets to URLs that may redirect across trust boundaries.
  • Rotate exposed API keys or tokens if logs show suspicious redirect paths.

Validation and detection

  • Inventory Node.js dependency manifests and lockfiles for follow-redirects below 1.16.0.
  • Identify outbound HTTP clients that send custom authentication headers.
  • Review redirect-handling paths for cross-domain redirects involving sensitive headers.
  • Confirm deployed artifacts include follow-redirects 1.16.0 or a vendor-fixed package.
  • Check proxy, application, and destination logs for unexpected redirected requests.
Prepared
Confidence
medium
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 · medium confidence lookup

CWE-200: Information exposure and cloud metadata lookup

Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. 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.

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cwe · low confidence lookup

CWE-212: 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.

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description · low confidence lookup

Credential and access behavior lookup

The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2026-40895 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:L/PR:N/UI:N/S:U/C:H/I:N/A:N

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
40Source links

SSVC decision data

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

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:L/PR:N/UI:N/S:U/C:H/I:N/A:N3.93.6redhat-SADP
6.9CVSS 4.0MediumCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N——GitHub_M

Vulnerability scoring details

Base CVSS 4.0 score

6.9Medium
CVSS 4.0 vector shape for CVE-2026-40895Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
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-SADPfollow-redirects: follow-redirects: Information disclosure via cross-domain redirects
other:Red Hat severity ratingcvssV3_1
  • 2026-04-21T21:02:33.280Z: Reported to Red Hat.
  • 2026-04-21T19:59:59.759Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
follow-redirectsfollow-redirects< 1.16.0Listed
Weakness

CWE details

CWE-200CWE-212

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

CWE-200 · source CWE mapping

Exposure of Sensitive Information to an Unauthorized Actor

Exposure of Sensitive Information to an Unauthorized Actor represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-212 · source CWE mapping

Improper Removal of Sensitive Information Before Storage or Transfer

Improper Removal of Sensitive Information Before Storage or Transfer represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs