CVE-2026-40993: Unfiltered Java Native Deserialization of SAML 2.0 Asserting Party Credentials BLOB Database Entry

Synopsis

Unfiltered Java native deserialization in Spring Security's SAML 2.0 asserting-party metadata repository allows an attacker with database write access to plant malicious serialized payloads in the saml2_asserting_party_metadata table. The vulnerability is reachable from an adjacent network, requires a high-privilege account, and involves high attack complexity due to the preconditions needed. Successful exploitation gives the attacker the ability to tamper with integrity-sensitive data and disrupt service availability. A patched-image rebuild at Spring Security 7.0.6 is available on HarborGuard for environments running an affected version (7.0.0 through 7.0.5).

HarborGuard Coverage

Exploit Conditions

• Network reachabilityDetail

  The attacker must be on an adjacent network, such as a shared LAN or VPN segment, to reach the database or application interface exposing the vulnerable table.

• AuthenticationRequired

  An admin-level or otherwise highly privileged database account is needed to write to the saml2_asserting_party_metadata table managed by JdbcAssertingPartyMetadataRepository.

• Victim interactionNot required

  No user action is required; the malicious payload executes when the application deserializes the stored credential columns without prompting any end user.

• Attack complexityDetail

  Exploitation involves non-trivial preconditions, specifically obtaining high-privilege database write access and crafting a valid serialized payload, making reliable exploitation environmentally dependent.

Blast Radius

• Attacker overwrites verification_credentials or encryption_credentials columns with crafted payloads, corrupting trust relationships for SAML 2.0 asserting parties.
• Integrity of the SAML metadata repository is compromised, allowing the attacker to substitute malicious signing or encryption keys used in federated authentication flows.
• Service availability is disrupted when the application attempts to deserialize the malicious payload, triggering uncaught exceptions or crashes in the SAML processing pipeline.
• Depending on the deserialization gadget chain present on the classpath, arbitrary code execution on the application host is a realistic outcome of successful payload delivery.