CVE-2026-43827 | Apache Shiro: Session fixation: new session is not created after login by default

Default configurations of Apache Shiro have a session fixation vulnerability. This issue affects Apache Shiro from 1.0 to 2.1.0, and 3.0.0-alpha-1. Users are recommended to upgrade to version 2.1.1, or 3.0.0-alpha-2 or later, which fixes the issue. In the affected versions, when a session already exists, it is not invalidated upon successful login, nor is a new session being generated with a new ID.

Published: 2026-05-25 Last update: 2026-05-28 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-43827 is rated Low Risk (30.4/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.06%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-43827

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-29 0.04% 0.06% +0.02%
2 2026-05-26 — 0.04% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-43827

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 4.0 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:N/VA:N/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:U/V:X/RE:L/U:Amber Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:P)
Additional preconditions must be present for exploitation.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:A)
User interaction is required in an active way.
Vulnerable system confidentiality impact (VC:H)
High confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:N)
No integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:N)
No availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:L)
Limited confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:Y)
Yes: all four kill-chain steps (reconnaissance, weaponization, delivery, exploitation) can be automated.
Recovery (supplemental) (R:U)
User: manual user intervention is needed to recover services.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:L)
Low/trivial response effort (documentation, simple configuration, low-touch guidance).
Provider urgency (supplemental) (U:AMBER)
Amber: provider rates moderate urgency.
 — — [email protected]
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 3.6 [email protected]

Weakness enumeration for CVE-2026-43827

GitHub Security Advisory for CVE-2026-43827

GHSA-fcvm-3cpj-f9qx · Severity: medium — Default configurations of Apache Shiro have a session fixation vulnerability. This issue affects...

OS Trackers for CVE-2026-43827

vendor priority summary link
debian not yet assigned CVE-2026-43827 not yet assigned priority: Debian including 1 source packages (shiro), 4 status rows across 4 suites (bookworm, bullseye, sid, trixie): open 4. https://security-tracker.debian.org/tracker/CVE-2026-43827
ubuntu medium CVE-2026-43827 medium priority: Ubuntu including 1 source packages (shiro), 7 status rows across 7 suites (bionic, focal, jammy, noble, questing, resolute, upstream): needs-triage 7. https://ubuntu.com/security/CVE-2026-43827

Affected software / configurations for CVE-2026-43827

Vendor Product Version Raw CPE
apache shiro < 2.1.1 cpe:2.3:a:apache:shiro:*:*:*:*:*:*:*:*
apache shiro 3.0.0 cpe:2.3:a:apache:shiro:3.0.0:alpha1:*:*:*:*:*:*

References for CVE-2026-43827

cvelogic Threat Intelligence