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High

SSRF in Spring Web Services WS-Addressing ReplyTo/FaultTo handling

IdentifiersCVE-2026-40999CWE-918· Server-Side Request Forgery (SSRF)

CVE-2026-40999 is a server-side request forgery vulnerability in Spring Web Services. When WS-Addressing is enabled and a request supplies non-anonymous ReplyTo or FaultTo addresses, Spring WS can initiate outbound connections via configured WebServiceMessageSender instances to destinations taken directly from those request headers. The framework does not verify that the supplied destinations are safe before connecting. As a result, attacker-controlled SOAP/WS-Addressing headers can influence server-side outbound requests. Affected versions are Spring Web Services 5.0.0 through 5.0.1, 4.1.0 through 4.1.3, 4.0.0 through 4.0.18, and 3.1.0 through 3.1.8.

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ANALYST BRIEF

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.

Successful exploitation allows an unauthenticated remote attacker to cause the vulnerable Spring WS application to make outbound requests to attacker-chosen destinations. This can expose internal network resources or services that are not directly reachable by the attacker and may disclose sensitive information returned through those server-initiated requests. The provided CVSS v3.1 vector indicates high confidentiality impact, no integrity impact, and no availability impact.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, disable or avoid use of WS-Addressing features that process non-anonymous ReplyTo or FaultTo addresses where feasible. Restrict or harden configured WebServiceMessageSender instances so they cannot reach arbitrary destinations, and enforce outbound network egress filtering to block access from the application to untrusted or internal-only endpoints except where explicitly required. Where possible, validate or reject untrusted ReplyTo and FaultTo header values at the application or gateway layer.

Remediation

Patch, then assume compromise.

Upgrade Spring Web Services to a fixed release once vendor patches are available from Spring. Specifically, organizations should move off affected versions 5.0.0-5.0.1, 4.1.0-4.1.3, 4.0.0-4.0.18, and 3.1.0-3.1.8 to the vendor-recommended patched versions referenced in the Spring security advisory for CVE-2026-40999.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

ACTIVITY FEED

Recent activity

6 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

6 SOURCESView more in app
What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
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Exposure mapping

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Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity5

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES
MITRE CVE
cve.org · CVE-2026-40999
NVD
nvd.nist.gov/vuln/detail/CVE-2026-40999
MITRE CWE · CWE-918
Server-Side Request Forgery (SSRF)
spring.io
spring.io/security/cve-2026-40999