Authentication Bypass in Apache Shiro shiro-guice Web Servlet Context
CVE-2026-56091 is an authentication bypass vulnerability in Apache Shiro affecting the shiro-guice module when it is deployed in a web servlet context. A specially crafted HTTP request can cause Shiro to incorrectly bypass authentication checks. The issue is described as similar to CVE-2020-1957, but impacts shiro-guice rather than shiro-spring. Based on the provided content, affected versions include all Apache Shiro releases through the 2.x line and 3.0.0-alpha-1 when using shiro-guice in a web servlet environment.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
shiro-guice module in a web servlet context until a fixed version can be deployed. Restrict external access to affected applications where feasible and review application-level access controls for sensitive endpoints. The provided content does not include any vendor-specified workaround beyond upgrading.Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
6 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An authentication bypass vulnerability in Apache Shiro's shiro-guice module when used in a web servlet context, triggered by a specially crafted HTTP request.
An authentication bypass vulnerability in Apache Shiro's shiro-guice module when used in a web servlet context, triggered by a specially crafted HTTP request.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.