CVE-2026-43827Network attack vector

Session hijacking via retained pre-login session ID

Published May 25, 2026 · Updated May 25, 2026

Session fixation in Apache Shiro 1.0 through 2.1.0 and 3.0.0-alpha-0 through 3.0.0-alpha-1 allows remote attackers to hijack sessions. The default authentication flow preserves an existing session and its identifier instead of invalidating it and issuing a new identifier after login. Exploitation requires an attacker to establish or learn the victim's pre-login session identifier and induce authentication, exposing data available to that session.

CVSS severity5.9
Medium
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Session fixation in Apache Shiro 1.0 through 2.1.0 and 3.0.0-alpha-0 through 3.0.0-alpha-1 allows remote attackers to hijack sessions. The default authentication flow preserves an existing session and its identifier instead of invalidating it and issuing a new identifier after login. Exploitation requires an attacker to establish or learn the victim's pre-login session identifier and induce authentication, exposing data available to that session.

The record

CVE
CVE-2026-43827
Published
May 25, 2026
Updated
May 25, 2026
Vendor
The Apache Software Foundation
Product
Apache Shiro
Classifications
CWE-384, CAPEC-21, CAPEC-61, CAPEC-60, CAPEC-31, CAPEC-196, CAPEC-59, CAPEC-39, T1550.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 25, 2026CVE publishedPublication date reported by the CVE source.
  2. May 25, 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=1.0 <=2.1.0
  2. Affected versionversion=3.0.0-alpha-0 <=3.0.0-alpha-1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Shiroversion=1.0 <=2.1.0; version=3.0.0-alpha-0 <=3.0.0-alpha-1

Published CVSS scores

6.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
5.9Apache Software FoundationCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:N/VA:N/SC:L/SI:N/SA: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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-384Session Fixation
CAPEC-21Exploitation of Trusted Identifiers
CAPEC-61Session Fixation
CAPEC-60Reusing Session IDs (aka Session Replay)
CAPEC-31Accessing/Intercepting/Modifying HTTP Cookies
CAPEC-196Session Credential Falsification through Forging
CAPEC-59Session Credential Falsification through Prediction
CAPEC-39Manipulating Opaque Client-based Data Tokens
T1550.004Use Alternate Authentication Material: Web Session Cookie

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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