Security readout for executives and security teams
Plain-English summary
Ruby applications using vulnerable ruby-jwt versions may accept forged HMAC-signed JWTs when verification uses an empty or missing key. If JWTs protect login sessions, API access, or authorization decisions, attackers could impersonate users or gain unauthorized access.
Executive priority
Treat as urgent for Ruby systems where JWTs control access. Prioritize internet-facing APIs, identity services, admin portals, and multi-tenant applications using the ruby-jwt gem with HMAC algorithms.
Technical view
Before ruby-jwt 2.10.3 and 3.2.0, HS256, HS384, and HS512 verification could succeed when the HMAC key was empty, nil, or returned that way by key lookup. Affected paths include JWT.decode and JWT::EncodedToken#verify_signature!.
Likely exposure
Exposure is likely in Ruby services using jwt versions below 2.10.3, or 3.x versions before 3.2.0, especially where HMAC JWT keys come from keyfinder logic or unknown key IDs.
Exploitation context
The source bundle reports no CISA KEV listing and provides no cited evidence of active exploitation. The issue is still high impact because it is network-reachable, unauthenticated, low complexity, and affects authentication integrity.
Researcher notes
Focus triage on HS256, HS384, and HS512 verification paths. The root issue is missing empty-key precondition enforcement around HMAC verification, not a named affected product beyond the ruby-jwt gem identified in the sources.
Mitigation direction
- Upgrade ruby-jwt to 2.10.3 or 3.2.0.
- Audit Gemfile.lock and dependency manifests for vulnerable jwt versions.
- Ensure HMAC JWT secrets are never empty or nil.
- Make key lookup failures reject tokens explicitly.
- Check vendor guidance for any additional hardening advice.
Validation and detection
- Confirm deployed services load ruby-jwt 2.10.3 or 3.2.0 or later.
- Search code for JWT.decode and JWT::EncodedToken#verify_signature! usage.
- Review keyfinder or key_finder logic for empty, nil, or nil-containing returns.
- Verify unknown key IDs are rejected, not mapped to empty keys.
- Review authentication logs for unusual JWT validation or key lookup failures.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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-1391: 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.
Open ATT&CK lookupCWE-287: Credential and account abuse lookup
Authentication and credential weaknesses can make valid-account abuse and credential telemetry useful review starting points. 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.
Open ATT&CK lookupCWE-326: 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.
Open ATT&CK lookupCredential 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.
Open ATT&CK lookupCVE-2026-45363 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.1 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
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.
SSVC decision data
CVSS vector scores
1 official scoreWe 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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N3.95.2GitHub_MVulnerability scoring details
Base CVSS 3.1 score
9.1CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/jwt/ruby-jwt/security/advisories/GHSA-c32j-vqhx-rx3xCVE reference, GitHub_M · x_refsource_CONFIRM
- https://github.com/jwt/ruby-jwt/commit/9820020869ad147b941e49d96ab8beba35532964CVE reference, GitHub_M · x_refsource_MISC
- https://github.com/jwt/ruby-jwt/commit/db560b769a07bd9724e77ff505011ac01872106fCVE reference, GitHub_M · x_refsource_MISC
- https://github.com/jwt/ruby-jwt/releases/tag/v2.10.3CVE reference, GitHub_M · x_refsource_MISC
- https://github.com/jwt/ruby-jwt/releases/tag/v3.2.0CVE reference, GitHub_M · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use of Weak Credentials
Use of Weak Credentials represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Improper Authentication
Improper Authentication represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Inadequate Encryption Strength
Inadequate Encryption Strength represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.