Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 0.36% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2026
CVE-2026-45363High confidence
`jwt` (Ruby gem) - empty-key HMAC bypass
jwt · ruby-jwt
Official source article: GitHub GHSA-C32J-VQHX-RX3X ↗. Check the applicable product and release in the original source.
9.1CriticalCVSS 3.1
Patch only the product branches with a verified fix
Fix availability varies by productCritical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityCritical→Operational priority:Critical, unchanged from published severity.unchanged
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs jwt ruby-jwt and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Remediation availability differs by product scope
Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
- Debian Security Tracker: 1 affected package state with no published fix
Distribution package intelligence
5 package statesRelease-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Package result overrides the generic status
BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 1 affected package state shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | ruby-jwt | Affected, no fix publishedDebian currently tracks this release as open. | Not published in this feed | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian bookwormbookworm · source | ruby-jwt | Vendor fix publishedDebian records a fixed source-package version for this release. | 2.5.0-1+deb12u1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian forkyforky · source | ruby-jwt | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.2.0-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian sidsid · source | ruby-jwt | Vendor fix publishedDebian records a fixed source-package version for this release. | 3.2.0-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | ruby-jwt | Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
Open-source package ranges4 source-attributed ranges
These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.
| Ecosystem and package | Affected range | First fixed version | Evidence |
|---|---|---|---|
| RubyGemsjwt | ECOSYSTEM: introduced 3.0.0; fixed 3.2.0 | 3.2.0 | OSV record ↗aggregator derived · 10 Sep 2026 |
| RubyGemsjwt | ECOSYSTEM: introduced 0; fixed 2.10.3 | 2.10.3 | OSV record ↗aggregator derived · 10 Sep 2026 |
| rubygemsjwt | >= 3.0.0, < 3.2.0 | 3.2.0 | GitHub advisory ↗upstream repository advisory · 2 Jun 2026 |
| rubygemsjwt | < 2.10.3 | 2.10.3 | GitHub advisory ↗upstream repository advisory · 2 Jun 2026 |
Direct vendor intelligence
1 currentAuthoritative 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.
CVE-2026-45363 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityruby-jwt: ruby-jwt: Authentication bypass due to empty key in HMAC verification
The vendor explicitly identifies these products as affected by this CVE.
- rubygem-jwt.src (satellite-capsule:el8) as a component of Red Hat Satellite 6
- rubygem-jwt (satellite-capsule:el8) as a component of Red Hat Satellite 6
- Summary
- A flaw was found in ruby-jwt, a Ruby implementation of the RFC 7519 OAuth JSON Web Token (JWT) standard. A remote attacker can exploit this vulnerability by crafting a malicious token that is accepted due to an empty key being used in the HMAC (Hash-based Message Authentication Code) digest calculation during token verification. This allows the attacker to bypass authentication and integrity checks, potentially leading to unauthorized access or data manipulation.
- Remediation
- Before applying this update, make sure all previously released errata relevant to your system have been applied. For detailed instructions how to apply this update, refer to: https://docs.redhat.com/en/documentation/red_hat_satellite/6.16/html/updating_red_hat_satellite/index
Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.
Fix availability varies by product01
What, why and how
ruby-jwt is a Ruby implementation of the RFC 7519 OAuth JSON Web Token standard. Prior to 2.10.3 and 3.2.0, JWT.decode(token, '', true, algorithm: 'HS256') accepts an attacker-forged token because OpenSSL::HMAC.digest('SHA256', '', payload) returns a valid digest under an empty key and no empty-key precondition exists in the HMAC algorithm. The same path is reached when a keyfinder block or key_finder: argument returns an empty string, nil, or an array containing nil for an unknown key, affecting HS256, HS384, and HS512 verification through JWT.decode and JWT::EncodedToken#verify_signature!. This issue is fixed in versions 2.10.3 and 3.2.0.
What
ruby-jwt is a Ruby implementation of the RFC 7519 OAuth JSON Web Token standard. Prior to 2.10.3 and 3.2.0, JWT.decode(token, '', true, algorithm: 'HS256') accepts an attacker-forged token because OpenSSL::HMAC.digest('SHA256', '', payload) returns a valid digest under an empty key and no empty-key precondition exists in the HMAC algorithm. The same path is reached when a keyfinder block or key_finder: argument returns an empty string, nil, or an array containing nil for an unknown key, affecting HS256, HS384, and HS512 verification through JWT.decode and JWT::EncodedToken#verify_signature!. This issue is fixed in versions 2.10.3 and 3.2.0.
Why
The affected component does not establish the requesting party's identity reliably before granting access.
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
ruby-jwt is a Ruby implementation of the RFC 7519 OAuth JSON Web Token standard. Prior to 2.10.3 and 3.2.0, JWT.decode(token, '', true, algorithm: 'HS256') accepts an attacker-forged token because OpenSSL::HMAC.digest('SHA256', '', payload) returns a valid digest under an empty key and no empty-key precondition exists in the HMAC algorithm. The same path is reached when a keyfinder block or key_finder: argument returns an empty string, nil, or an array containing nil for an unknown key, affecting HS256, HS384, and HS512 verification through JWT.decode and JWT::EncodedToken#verify_signature!. This issue is fixed in versions 2.10.3 and 3.2.0.
Why
The affected component does not establish the requesting party's identity reliably before granting access.
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 No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Improper Authentication → 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
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-287 ↗
CWE-287: Improper Authentication. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NCommon Vulnerability Scoring System 3.1: 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.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.ANoneAvailability impact: No direct loss is represented by this metric.- Post-exploitation / living off the land
- Stolen credentials, tokens and legitimate administration functions may provide continued access without deploying a large custom toolset.
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. - Fix availability varies by product
- Affected
- Fixed
- rubygem-jwt-0:2.10.3-1.el8sat.noarch as a component of Red Hat Satellite 6.16 for RHEL 8
- rubygem-jwt-0:2.10.3-1.el8sat.src as a component of Red Hat Satellite 6.16 for RHEL 8
- rubygem-jwt-0:2.10.3-1.el9sat.noarch as a component of Red Hat Satellite 6.16 for RHEL 9
- rubygem-jwt-0:2.10.3-1.el9sat.src as a component of Red Hat Satellite 6.16 for RHEL 9
- ansible-core-1:2.16.19-1.el9sat.noarch as a component of Red Hat Satellite 6.17 for RHEL 9
- ansible-core-1:2.16.19-1.el9sat.src as a component of Red Hat Satellite 6.17 for RHEL 9
- ansible-test-1:2.16.19-1.el9sat.noarch as a component of Red Hat Satellite 6.17 for RHEL 9
- rubygem-jwt-0:2.10.3-1.el9sat.noarch as a component of Red Hat Satellite 6.17 for RHEL 9
- rubygem-jwt-0:2.10.3-1.el9sat.src as a component of Red Hat Satellite 6.17 for RHEL 9
- pulpcore-obsolete-packages-0:1.3.1-5.el9pc.noarch as a component of Red Hat Satellite 6.18 for RHEL 9
- pulpcore-obsolete-packages-0:1.3.1-5.el9pc.src as a component of Red Hat Satellite 6.18 for RHEL 9
- python3.12-pulpcore-0:3.73.30-3.el9pc.noarch as a component of Red Hat Satellite 6.18 for RHEL 9
- python3.12-pulpcore-0:3.73.30-3.el9pc.src as a component of Red Hat Satellite 6.18 for RHEL 9
- rubygem-jwt-0:2.10.3-1.el9sat.noarch as a component of Red Hat Satellite 6.18 for RHEL 9
- rubygem-jwt-0:2.10.3-1.el9sat.src as a component of Red Hat Satellite 6.18 for RHEL 9
- rubygem-jwt-0:2.10.3-1.el9sat.noarch as a component of Red Hat Satellite 6.19 for RHEL 9
- rubygem-jwt-0:2.10.3-1.el9sat.src as a component of Red Hat Satellite 6.19 for RHEL 9
- Action
- Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
- 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 14 Jul 2026 · Last source change 19 Sept 2026, 18:07 UTC · CWE-287 · Improper Authentication
CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2026-44516
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD not scheduled
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Affected versionsThe structured affected or fixed version information changed.Red Hat Product Security ↗
- Before
- ruby-jwt: < 2.10.3, >= 3.0.0, < 3.2.0 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- ruby-jwt: < 2.10.3, >= 3.0.0, < 3.2.0 · Fixed: Before applying this update, make sure all previously released errata relevant to your system have been applied. For detailed instructions how to apply this update, refer to: https://docs.redhat.com/en/documentation/red_hat_satellite/6.16/html/updating_red_hat_satellite/index
- Remediation statusRemediation status changed from Awaiting fix to Patch available.Red Hat Product Security ↗
- Before
- Awaiting fix
- After
- Patch available
- Affected versionsThe structured affected or fixed version information changed.CNA ↗
- Before
- < 2.10.3; >= 3.0.0, < 3.2.0 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
- After
- ruby-jwt: < 2.10.3, >= 3.0.0, < 3.2.0 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
CVE published
Fixed release recorded from official guidance
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.