CVE-2026-40973

Session hijacking and code execution via temp-directory takeover

Published Apr 27, 2026 · Updated Apr 27, 2026

Insecure temporary-directory handling in affected Spring Boot releases allows local users to hijack sessions or execute code. ApplicationTemp accepts a predictable, symlink-controlled directory without verifying its ownership, allowing another host account to control persisted session storage. Exploitation requires persistent servlet sessions, control that survives an application restart, and usable session data or a deserialization gadget chain.

CVSS severity7.0
High
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insecure temporary-directory handling in affected Spring Boot releases allows local users to hijack sessions or execute code. ApplicationTemp accepts a predictable, symlink-controlled directory without verifying its ownership, allowing another host account to control persisted session storage. Exploitation requires persistent servlet sessions, control that survives an application restart, and usable session data or a deserialization gadget chain.

The record

CVE
CVE-2026-40973
Published
Apr 27, 2026
Updated
Apr 27, 2026
Vendor
Spring
Product
Spring Boot
Classifications
CWE-377, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.7.0 <2.7.33
  2. Affected versionversion=3.3.0 <3.3.19
  3. Affected versionversion=3.4.0 <3.4.16
  4. Affected versionversion=3.5.0 <3.5.14
  5. Affected versionversion=4.0.0 <4.0.6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Spring · Spring Bootversion=2.7.0 <2.7.33; version=3.3.0 <3.3.19; version=3.4.0 <3.4.16; version=3.5.0 <3.5.14; version=4.0.0 <4.0.6

Published CVSS scores

7.0VMwareCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-377Insecure Temporary File
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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