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CVE-2026-11800: Org.keycloak:keycloak-services: keycloak: authentication bypass via jwt algorithm confusion

Noroxi assessment

Priority: Monitor (action score 32/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.26% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: org.keycloak:keycloak-services (Maven) 26.6.4.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to org.keycloak:keycloak-services (Maven) 26.6.4 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

A flaw was found in Keycloak. This JWT algorithm confusion vulnerability in the JWT Authorization Grant flow allows an attacker with valid client credentials to bypass signature verification. By forging an assertion, the attacker can create unauthorized access tokens. This enables the attacker to impersonate any federated user linked to the affected Identity Provider, leading to unauthorized access and potential privilege escalation.

HighCVSS 8.1 · v3.1—Proof of concept Fix available
Published
Jun 25, 2026
Updated
Oct 25, 2026
EPSS
0.2% · 18th percentile

Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
32 / 40 · 8.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · redhat
8.1
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
redhatbuild of keycloak

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • redhat build of keycloak26.6 and later · before 26.6.4

Versions reported by the vendor

Affected version ranges reported by the assigning authority (redhat). Independent of NVD's CPE analysis and usually ahead of it.

  • Red Hat Red Hat Build of Keycloak

    • all versionsaffected
    • all versionsunknown

  • Red Hat Red Hat build of Keycloak 26.6

    • 26.6.4-2 and laternot affected · rpm
    • 26.6-8 and laternot affected · rpm
    • 26.6-8 and laternot affected · rpm

  • Red Hat Red Hat build of Keycloak 26.6.4

    • all versionsunknown

  • Red Hat Red Hat Data Grid 8

    • all versionsunknown

  • Red Hat Red Hat JBoss Enterprise Application Platform Expansion Pack

    • all versionsunknown

  • Red Hat Red Hat Single Sign-On 7

    • all versionsunknown

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Mavenorg.keycloak:keycloak-servicesbefore 26.6.426.6.4

Same product

redhat: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-16442Keycloak-services: keycloak-services: saml idp-initiated broker login bypasses link-only restriction
    39Monitor
  • CVE-2026-16443Keycloak-services: keycloak-services: saml broker metadata import disables response signature validation
    36Monitor
  • CVE-2026-15572Keycloak-services: keycloak-services: dcr protocol mapper type-swap policy bypass allows privilege escalation
    35Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-9799Jun 25, 2026 · Keycloak: keycloak: unauthorized access to resources via uma permission ticket bypass
    18Monitor
  • ← EarlierCVE-2026-9800Jun 25, 2026 · Keycloak-policy-enforcer: keycloak policy enforcer: authorization bypass via incorrect uri comparison
    32Monitor
  • Later →CVE-2026-14209Jun 30, 2026 · Keycloak-admin-ui: keycloak-admin-ui:admin ui extension brute-force-user endpoint bypasses fgapv2 user view restrictions
    17Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Maven:org.keycloak:keycloak-services26.6.4Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×3

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02026-11-09
Proof-of-concept repository on GitHubstars:02026-11-10
Proof-of-concept repository on GitHubstars:02026-11-10

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

  1. Published
  2. First PoC+136 d
  3. TodayNov 11, 2026+139 d

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-1644341 days apartKeycloak-services: keycloak-services: saml broker metadata import disables response signature validation
    36Monitor
  • CVE-2026-979328 days apartKeycloak: keycloak: security policy bypass in jwe-encrypted request object processing
    30Monitor
  • CVE-2026-1856940 days apartKeycloak-services: keycloak-services: oidc backchannel logout accepts unsigned forged logout tokens
    14Monitor
  • CVE-2025-12150118 days apartOrg.keycloak/keycloak-services: webauthn attestation statement verification bypass
    12Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

  • CVE-2026-90860 days apartKeycloak: keycloak: cross-site scripting (xss) via case-insensitive uri validation bypass
    29Monitor
  • CVE-2026-90830 days apartKeycloak: keycloak: information disclosure through arbitrary filesystem path probing
    19Monitor
  • CVE-2026-3798072 days apartOrg.keycloak.forms.login: keycloak: keycloak: arbitrary code execution via stored cross-site scripting (xss) in organization selection login page
    19Monitor
  • CVE-2026-487491 days apartOrg.keycloak.protocol.oidc.grants: org.keycloak.services.managers: keycloak: server-side request forgery via oidc token endpoint manipulation
    12Monitor

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
None

Weakness class (CWE)

CWE-347 · Improper Verification of Cryptographic Signature

CVSS vector

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

nvd-secondary

Root cause

The verifier takes the algorithm to verify with from the token’s own header. Untrusted data ends up deciding its own verification rule.

The bug in code

The whole CWE-347 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

ts
const claims = jwt.verify(token, publicKey);

Fixed

ts
const claims = jwt.verify(token, publicKey, {  algorithms: ["RS256"],  issuer: "https://id.example.com",  audience: "portal",});

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Exploit maturitynone → poc
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records