How severe is CVE-2026-43827?

No CVSS score has been assigned to CVE-2026-43827 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-43827?

CVE-2026-43827 affects the following packages: org.apache.shiro:shiro-core (Maven), org.apache.shiro:shiro-core (Maven). Ecosystems affected: Maven.

How do I fix CVE-2026-43827?

Update org.apache.shiro:shiro-core to 2.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-43827 is resolved across your whole dependency graph.

How do I detect CVE-2026-43827 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.shiro:shiro-core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2026-43827 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-43827?

O3 pinpoints whether CVE-2026-43827 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2026-43827 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-43827 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-43827?

CVE-2026-43827 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 34th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-43827?

CVE-2026-43827 is classified as CWE-384 (CWE-384). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-43827 published, and has it been updated?

CVE-2026-43827 was published on May 26, 2026 and was last updated on June 30, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕ Maven

Not in CISA KEV

CVE-2026-43827

CVE-2026-43827 is a CWE-384 vulnerability in org.apache.shiro:shiro-core. O3 Security confirms whether CVE-2026-43827 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Apache Shiro has a session fixation vulnerability

Published

May 26, 2026

Updated

Jun 30, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Aug 15, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-43827.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs34th percentile — riskier than 34% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

2 pkgs affected

☕org.apache.shiro:shiro-core☕org.apache.shiro:shiro-core

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.apache.shiro:shiro-core`	≥ 1.0.0-incubating&&< 2.2.0	2.2.0
☕Maven	`org.apache.shiro:shiro-core`	≥ 3.0.0-alpha-1&&< 3.0.0-alpha-2	3.0.0-alpha-2

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.shiro:shiro-core. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update org.apache.shiro:shiro-core to 2.2.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-43827 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-43827 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-43827. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

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.

O3 Security · Impact-Aware SCA

Is CVE-2026-43827 in your dependencies?

O3 detects CVE-2026-43827 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works