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Full vulnerability report · 2026
CVE-2026-28802High confidence

Authlib: Setting `alg: none` and a blank signature appears to bypass signature verification

authlib · authlib

7.7HighCVSS 4.0
Recommended action
Within 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-28802 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityauthlib: Authlib: Signature verification bypass via malicious JWT allows unauthorized access
1 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • satellite/foreman-mcp-server-rhel9 as a component of Red Hat Satellite 6
Summary
A flaw was found in Authlib, a Python library for building OAuth and OpenID Connect servers. A remote attacker can exploit this vulnerability by crafting a malicious JSON Web Token (JWT) with a "none" algorithm and an empty signature. This bypasses the expected signature verification, potentially allowing the attacker to forge tokens and gain unauthorized access or perform unauthorized actions within applications using Authlib.
Remediation
Before applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://docs.redhat.com/en/documentation/red_hat_ansible_automation_platform/2.6#Upgrade
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-10009

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

Authlib is a Python library which builds OAuth and OpenID Connect servers. From version 1.6.5 to before version 1.6.7, previous tests involving passing a malicious JWT containing alg: none and an empty signature was passing the signature verification step without any changes to the application code when a failure was expected.. This issue has been patched in version 1.6.7.

What

Authlib is a Python library which builds OAuth and OpenID Connect servers. From version 1.6.5 to before version 1.6.7, previous tests involving passing a malicious JWT containing alg: none and an empty signature was passing the signature verification step without any changes to the application code when a failure was expected.. This issue has been patched in version 1.6.7.

Why

The product does not verify, or incorrectly verifies, the cryptographic signature for data.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Authlib is a Python library which builds OAuth and OpenID Connect servers. From version 1.6.5 to before version 1.6.7, previous tests involving passing a malicious JWT containing alg: none and an empty signature was passing the signature verification step without any changes to the application code when a failure was expected.. This issue has been patched in version 1.6.7.

Why

The product does not verify, or incorrectly verifies, the cryptographic signature for data.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Improper Verification of Cryptographic Signature → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-347 ↗

CWE-347: Improper Verification of Cryptographic Signature. The product does not verify, or incorrectly verifies, the cryptographic signature for data.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P

Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCNoneVulnerable-system confidentiality: No direct loss is represented by this metric.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VANoneVulnerable-system availability: No direct loss is represented by this metric.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-347Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-W-2026-0935Red Hat Ansible Automation Platform: Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Red Hat Ansible Automation Platform ausnutzen, um einen Denial of Service Angriff durchzuführen, beliebigen Code auszuführen, Sicherheitsmaßnahmen zu umgehen, Daten zu manipulieren, vertrauliche Informationen offenzulegen oder Cross-Site-Scripting-Angriffe durchzuführen.

Official advisory
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
satellite/foreman-mcp-server-rhel9 as a component of Red Hat Satellite 6
Fixed
registry.redhat.io/ansible-automation-platform-26/lightspeed-chatbot-rhel9@sha256:111c3fa869282760a7408db240e5fbddd74816fa5ffc12578c267427eae8eb96_ppc64le as a component of Red Hat Ansible Automation Platform 2.6; registry.redhat.io/ansible-automation-platform-26/lightspeed-chatbot-rhel9@sha256:20ceae5ef8be4bc9ccc0e0f3b495a7f3f3bf5ba790dc4f91d33b063457974ca6_arm64 as a component of Red Hat Ansible Automation Platform 2.6; registry.redhat.io/ansible-automation-platform-26/lightspeed-chatbot-rhel9@sha256:6c5f0d6ede717eb230efb7676cc320a96ab6667f81d8f0a52a22b5a3986de163_s390x as a component of Red Hat Ansible Automation Platform 2.6; registry.redhat.io/ansible-automation-platform-26/lightspeed-chatbot-rhel9@sha256:d17dce8e1cc199e35217043b9b80a0d748520cf40204713ba872b5ce14ebf7cc_amd64 as a component of Red Hat Ansible Automation Platform 2.6; registry.redhat.io/quay/quay-rhel8@sha256:2f62df99c2b7697461a2865380344c90a6fb8aec7b279f8f2f6e0684b662d19f_amd64 as a component of Red Hat Quay 3.12; registry.redhat.io/quay/quay-rhel8@sha256:4076a739c16c0567def8339bff5e8adca2f995217ae55428061cd0136a7e7a21_arm64 as a component of Red Hat Quay 3.12; registry.redhat.io/quay/quay-rhel8@sha256:56bcc55b01c76a1eb7ad8b265cf9dfdd488fc62bc353e3822864a0f6c4f98ffb_ppc64le as a component of Red Hat Quay 3.12; registry.redhat.io/quay/quay-rhel8@sha256:e39ee513b081c979409b52c41db9222496868b3910c01b5c04de6f3206f467b5_s390x as a component of Red Hat Quay 3.12; registry.redhat.io/quay/quay-rhel8@sha256:8acebb6bd51def60517b03f92103cecfadfc8e7fce42e4a002cb9c9271915b6b_ppc64le as a component of Red Hat Quay 3.15; registry.redhat.io/quay/quay-rhel8@sha256:be166b843cc21b3942850443c0f802406f397f71959654a45e17a24fdcb0606a_s390x as a component of Red Hat Quay 3.15; registry.redhat.io/quay/quay-rhel8@sha256:c72dd9dd58db8ebcdc9b4daa433840411636e3dea82b21ca191fd0d272e636ec_amd64 as a component of Red Hat Quay 3.15; registry.redhat.io/quay/quay-rhel9@sha256:139cae64e4790ebf8b760c6376a33d15233222a25e4da39c6062d7e46c3a1bef_amd64 as a component of Red Hat Quay 3.16; registry.redhat.io/quay/quay-rhel9@sha256:52883f389182907dec0e286d626c4faea0f4ae29a5d0e841d6ad2287fdb964c2_arm64 as a component of Red Hat Quay 3.16; registry.redhat.io/quay/quay-rhel9@sha256:ad162e6ea2f6fd246f605180699ce36e4ea91c4b551c7af600a64e671a303ee9_s390x as a component of Red Hat Quay 3.16; registry.redhat.io/quay/quay-rhel9@sha256:f6a15c2f1b4d5900cdbd366080e40d3a90d51ba9e5b4d6196e15eefe69d902c3_ppc64le as a component of Red Hat Quay 3.16; registry.redhat.io/quay/quay-rhel8@sha256:6e13793ca8f309ec0b69ae609b840ff0f41989d88cd4bba127e1b0040631367e_ppc64le as a component of Red Hat Quay 3.1; registry.redhat.io/quay/quay-rhel8@sha256:c0d00643c4ac6f84e5327192a29c6353b5dcac34d483d0a3e5f39d366127fcc2_amd64 as a component of Red Hat Quay 3.1; registry.redhat.io/quay/quay-rhel8@sha256:f6a231ebb14c74e194a8091822fe6a981e1cec92d223e04e6d0f12b60206259a_s390x as a component of Red Hat Quay 3.1; registry.redhat.io/quay/quay-rhel8@sha256:3e5ce0a56241c9804249dfb302cde02d2ffe30ba8fcd8aef8f1bce916d2324ad_ppc64le as a component of Red Hat Quay 3.9; registry.redhat.io/quay/quay-rhel8@sha256:d64bb14bf73ef1bc222525bffb67a3dfab0ba3ceef4770beb8138699609d4b41_s390x as a component of Red Hat Quay 3.9; registry.redhat.io/quay/quay-rhel8@sha256:dd567423c854e8732542c41bfcda71948517762f8e91e31496e7dffa67b3c8c0_amd64 as a component of Red Hat Quay 3.9
Action
Before applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://docs.redhat.com/en/documentation/red_hat_ansible_automation_platform/2.6#Upgrade
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 6 Mar 2026 · Last source change 17 Aug 2026, 12:05 UTC · CWE-347 · Improper Verification of Cryptographic Signature

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-10009
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates →

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-10009↗Vendor CSAF · Red Hat Product Security↗Public exploit reference↗Patch or update reference↗Patch or update reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-28802 · cve.blacktree.nl