Security readout for executives and security teams
Plain-English summary
Apache Shiro can expose protected static files when an application runs on a case-insensitive filesystem and its security filters match only lowercase paths. An unauthenticated remote requester may obtain those files by changing filename capitalization. The reported impact is limited to confidentiality; dynamic application content is not identified as affected.
Executive priority
Treat this as a focused, moderate-priority remediation. Promptly assess externally reachable Shiro applications containing sensitive static files, especially development or production deployments on case-insensitive storage. Accelerate upgrading where the required filesystem and filter conditions exist; lower priority where static files are public or storage is demonstrably case-sensitive.
Technical view
CVE-2026-23903 is a CWE-289 alternate-name authentication bypass affecting Apache Shiro before 2.0.7. Exploitation requires static files on a case-insensitive filesystem and case-sensitive filter-chain rules. Its CVSS 3.1 score is 5.3: network-accessible, low complexity, unauthenticated, no user interaction, with low confidentiality impact and no reported integrity or availability impact.
Likely exposure
Exposure is conditional, not universal. Prioritize internet-facing applications using Apache Shiro before 2.0.7 that protect static files through lowercase path filters while serving from case-insensitive filesystems, including default macOS setups. The supplied record does not identify other affected products or filesystems.
Exploitation context
The CVSS vector indicates remote, unauthenticated exploitation with low complexity and no user interaction. However, the supplied bundle marks the CVE as absent from KEV and provides no evidence of active exploitation or public weaponization. Impact is limited to unauthorized access to static files under the stated conditions.
Researcher notes
The vulnerability concerns path identity differences between Shiro filter matching and case-insensitive filesystem resolution. Apache states that only static files are affected. Shiro 2.1.0 introduced explicit case-insensitive parameters; defaults expand in 3.0.0 for shiro.ini and 3.0.1 for all configurations. The bundle does not document exploitation telemetry.
Mitigation direction
- Upgrade Apache Shiro to version 2.0.7 or later, as recommended by Apache.
- On Shiro 2.1.0 or later, enable the documented case-insensitive filter-chain setting.
- Review protected static files and remove sensitive information that does not need web exposure.
- Confirm configuration defaults when adopting Shiro 3.0.0 or 3.0.1 and later.
Validation and detection
- Inventory applications using org.apache.shiro:shiro-web and record their deployed Shiro versions.
- Determine whether protected static files reside on a case-insensitive filesystem.
- Review filter-chain path rules for lowercase-only or otherwise case-sensitive matching.
- After remediation, verify unauthorized requests cannot retrieve protected static files using alternate filename capitalization.
- Confirm the intended case-insensitive setting is active in each deployment configuration style.
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-289: 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-2026-23903 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
- Medium
- CVSS
- 5.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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:L/I:N/A:N3.91.4CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
5.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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://lists.apache.org/thread/5jjf0hnjcol58z2m5y255c7scz1lnp8kCVE reference, apache · vendor-advisory
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.
Authentication Bypass by Alternate Name
Authentication Bypass by Alternate Name represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.