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Response snapshot Oct 27, 2026, 05:34 UTC

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VulnerabilityCVE-2026-42272

Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service.

Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.14, Heimdall handles URL-encoded slashes (%2F) in a case-sensitive manner, while percent-encoding is defined to be case-insensitive.

At a glance

Exploited
Not known
Severity
7.8 High (CVSS 4.0)
Chance of exploitation
0.4% in the next 30 days
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-42272 (opens a new tab)

What happened

Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.14, Heimdall handles URL-encoded slashes (%2F) in a case-sensitive manner, while percent-encoding is defined to be case-insensitive. As a result, the lowercase equivalent (%2f) is not recognized and therefore not processed as expected when allow_encoded_slashes is set to off (the default setting).

This discrepancy can lead to differences in how request paths are interpreted by heimdall and upstream components, which may result in authorization bypass. This issue has been patched in version 0.17.14.

Scores and how they were measured

CVSS base severity

7.8

Version 4.0As of

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Measurement source (opens a new tab)

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

EPSS probability

0.4%

Scored Percentile 33.6%

Model and measurement source (opens a new tab)

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

Sources

  1. Primary source

    NVD CVE-2026-42272 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  4. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  5. Primary source

    FIRST measured EPSS score (opens a new tab)

    Measured EPSS probability and percentile for CVE-2026-42272, scored 2026-10-26. This is a model estimate, not proof of exposure.

    Published Checked

Cite this record

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

APA

KEVWire. (2026, October 26). Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. (CVE-2026-42272). https://kevwire.com/record/CVE-2026-42272

MLA

"Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. (CVE-2026-42272)." KEVWire, 26 Oct. 2026, kevwire.com/record/CVE-2026-42272.

Chicago

KEVWire. "Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. (CVE-2026-42272)." Last modified October 26, 2026. https://kevwire.com/record/CVE-2026-42272.

Evidence summary (plain text)

Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. (May 8, 2026).
Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.14, Heimdall handles URL-encoded slashes (%2F) in a case-sensitive manner, while percent-encoding is defined to be case-insensitive. As a result, the lowercase equivalent (%2f) is not recognized and therefore not processed as expected when allow_encoded_slashes is set to off (the default setting). This discrepancy can lead to differences in how request paths are interpreted by heimdall and upstream components, which may result in authorization bypass. This issue has been patched in version 0.17.14.
CVSS 7.8 (version 4.0; evidence as of Oct 26, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-42272).
EPSS 0.4% for the following 30 days, scored Oct 26, 2026 (https://api.first.org/data/v1/epss?cve=CVE-2026-42272&date=2026-10-26).
Sources:
NVD CVE-2026-42272: https://nvd.nist.gov/vuln/detail/CVE-2026-42272
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T20:05:59.720Z&lastModEndDate=2026-10-26T21:35:56.549Z&resultsPerPage=500&startIndex=1500
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T19:31:27.927Z&lastModEndDate=2026-10-26T21:05:56.246Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-26T19:01:15.495Z&lastModEndDate=2026-10-26T20:30:55.133Z&resultsPerPage=500&startIndex=500
FIRST measured EPSS score: https://api.first.org/data/v1/epss?cve=CVE-2026-42272&date=2026-10-26
Record ID: CVE-2026-42272.
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 27, 2026, 01:40 UTC. Ingestion is not an independent editorial investigation.

NVD status: Deferred. Publication in the NVD is not evidence of exploitation.

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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Record details

Record detail