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CVE-2026-40976 is a missing-authorization vulnerability in Spring Boot 4.0.0 through 4.0.5. In affected servlet-based applications, a conditional check in the default management security auto-configuration can omit the authorization configuration when Actuator auto-configuration is present but the separate health module is absent. Consequently, the default Spring Security filter chain does not protect application endpoints.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
The repository consists of one Python 3 script, poc.py, claiming a proof of concept for CVE-2026-40976 affecting Spring Boot 4.0.0-4.0.5. It automatically installs the requests dependency with pip if absent, accepts a target base URL as a command-line argument, and suppresses TLS certificate warnings while making requests with certificate verification disabled. The script first sends an unauthenticated GET to /actuator and treats HTTP 200 as evidence of an authentication bypass. It then parses the response's _links object to enumerate available Actuator routes, probes env, configprops, beans, threaddump, mappings, and health routes for unauthenticated exposure, and finally POSTs to standard and custom shutdown routes. Its main impact is potential remote denial of service when shutdown is exposed; its reconnaissance can also identify sensitive Actuator information exposure. The script does not contain a protocol-level bypass technique, authentication token manipulation, or version verification, so HTTP 200 results may also reflect intentionally unauthenticated Actuator configuration and can produce false positives for the claimed CVE.
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27 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A vulnerability identified as CVE-2026-40976 involving Spring Boot Actuator exposure, with references to the /actuator/env endpoint and disclosure of environment-related information such as propertySources and activeProfiles.
A Spring Boot default web security bypass vulnerability mentioned as background vendor security history.
A separate Spring Boot security bypass vulnerability mentioned only as related background.
An authorization bypass vulnerability in Spring Boot where default web security can be ineffective under specific conditions, allowing unauthorized access to all endpoints.
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.