CVE-2023-20866Network attack vector

Session hijacking via printed session identifiers

Published Apr 13, 2023 · Updated Feb 7, 2025

Information exposure in Spring Session 3.0.0 allows attackers with application-log access to obtain session IDs from standard output. HeaderHttpSessionIdResolver.resolveSessionIds reads the configured request header and prints its value with System.out.println before returning it. Only applications using HeaderHttpSessionIdResolver are affected; log readers can reuse exposed identifiers to hijack sessions.

CVSS severity6.5
Medium
EPSS probability0.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Information exposure in Spring Session 3.0.0 allows attackers with application-log access to obtain session IDs from standard output. HeaderHttpSessionIdResolver.resolveSessionIds reads the configured request header and prints its value with System.out.println before returning it. Only applications using HeaderHttpSessionIdResolver are affected; log readers can reuse exposed identifiers to hijack sessions.

The record

CVE
CVE-2023-20866
Published
Apr 13, 2023
Updated
Feb 7, 2025
Vendor
VMware
Product
Spring Session
Classifications
CWE-200, T1552.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 13, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 7, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=Spring session versions 3.0.x prior to 3.0.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

VMware · Spring Sessionversion=Spring session versions 3.0.x prior to 3.0.1

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
T1552.001Unsecured Credentials: Credentials In Files

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo