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MEDIUM severity

CVE-2023-34396 — struts2-core

MEDIUMFix: apache/struts@2d6f1bc

CVE-2023-34396 is a medium-severity (CVSS 4.3) CWE-770 vulnerability in org.apache.struts:struts2-core. A fix is available for org.apache.struts:struts2-core — see the affected versions and patch details below.

Apache Struts: DoS via OOM owing to no sanity limit on normal form fields in multipart forms

Also known asGHSA-4g42-gqrg-4633
Published
Updated
Affected
4 pkgs
Patched
2 / 4
Exploits
None indexed
Exploitation data as of Nov 5, 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-2023-34396.

EPSS Exploitation Probability

via FIRST.org ↗
5.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs93th percentile — riskier than 93% of all scored CVEsHighest risk
0.00%2.38%4.75%7.13%0.1%5.5%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

4 pkgs affected
☕org.apache.struts:struts2-core☕org.apache.struts:struts2-core☕org.apache.struts:struts-core☕struts:struts

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

Denial of service via out of memory (OOM) owing to no sanity limit on normal form fields in multipart forms. When a Multipart request has non-file normal form fields, Struts used to bring them into memory as Strings without checking their sizes. This could lead to an OOM if developer has set struts.multipart.maxSize to a value equal or greater than the available memory.

Upgrade to Struts 2.5.31 or 6.1.2.1 or greater

Affected Packages

4 total 2 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.apache.struts:struts2-coreall versions2.5.31org.apache.struts:struts2-core:2.5.31
☕Mavenorg.apache.struts:struts2-core≥ 6.0.0&&< 6.1.2.16.1.2.1org.apache.struts:struts2-core:6.1.2.1
☕Mavenorg.apache.struts:struts-coreall versionsNo fix
☕Mavenstruts:strutsall versionsNo fix

Affected Products

1 product · 2 configurations
Application
strutsapache
≥ 6.0.0 && < 6.1.2.1
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.struts:struts2-core, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.apache.struts:struts2-core to 2.5.31 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-34396 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

Denial of service via out of memory (OOM) owing to no sanity limit on normal form fields in multipart forms. When a Multipart request has non-file normal form fields, Struts used to bring them into memory as Strings without checking their sizes. This could lead to an OOM if developer has set struts.multipart.maxSize to a value equal or greater than the available memory. Upgrade to Struts 2.5.31 or 6.1.2.1 or greater
O3 Security · Impact-Aware SCA

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CVE-2023-34396: struts2-core DoS — Fixed in 2.5.31