CVE-2007-4556

Severity: medium (CVSS 6.8 v2.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 25.7% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2007-08-28 · updated 2026-06-16

Description

Struts support in OpenSymphony XWork before 1.2.3, and 2.x before 2.0.4, as used in WebWork and Apache Struts, recursively evaluates all input as an Object-Graph Navigation Language (OGNL) expression when altSyntax is enabled, which allows remote attackers to cause a denial of service (infinite loop) or execute arbitrary code via form input beginning with a "%{" sequence and ending with a "}" character.

Affected products

Opensymphony Xwork: before 1.2.3; from 2.0.0 through 2.0.4 — fixed in 1.2.3

How to fix

Upgrade to a fixed version: Opensymphony Xwork 1.2.3. Check the vendor advisory for mitigations.

References

http://forums.opensymphony.com/ann.jspa?annID=54
http://issues.apache.org/struts/browse/WW-2030
http://jira.opensymphony.com/browse/XW-544
http://jira.opensymphony.com/secure/ReleaseNote.jspa?projectId=10050&styleName=Html&version=21701
http://jira.opensymphony.com/secure/ReleaseNote.jspa?projectId=10050&styleName=Html&version=21706
http://osvdb.org/37072
http://secunia.com/advisories/26681
http://secunia.com/advisories/26693
http://secunia.com/advisories/26694
http://struts.apache.org/2.x/docs/s2-001.html
http://wiki.opensymphony.com/display/WW/1.2.3+Press+Release
http://www.securityfocus.com/bid/25524

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