CVE-2007-4556

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.

Published: 2007-08-28 Last update: 2026-04-23 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2007-4556 is rated Moderate Risk (56.2/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.07%). Review affected assets and schedule remediation.

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-2007-4556

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 2026-02-22 2.36% 2.07% -0.29%
2 2025-06-16 2.21% 2.36% +0.15%
3 2025-05-17 — 2.21% —

Full EPSS history (20 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2007-4556

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.8 2.0 MEDIUM
AV:N/AC:M/Au:N/C:P/I:P/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:P)
Partial confidentiality impact.
Integrity impact (I:P)
Partial integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 6.4 [email protected]

Weakness enumeration for CVE-2007-4556

GitHub Security Advisory for CVE-2007-4556

GHSA-h7mf-qrm9-2848 · Severity: medium · Ecosystem: maven — OpenSymphony XWork vulnerable to improper input validation

Affected software / configurations for CVE-2007-4556

Vendor Product Version Raw CPE
opensymphony xwork < 1.2.3 cpe:2.3:a:opensymphony:xwork:*:*:*:*:*:*:*:*
opensymphony xwork >= 2.0.0, <= 2.0.4 cpe:2.3:a:opensymphony:xwork:*:*:*:*:*:*:*:*

References for CVE-2007-4556

URL Tags
http://forums.opensymphony.com/ann.jspa?annID=54 Patch Vendor Advisory
http://issues.apache.org/struts/browse/WW-2030 Third Party Advisory
http://jira.opensymphony.com/browse/XW-544 Vendor Advisory
http://jira.opensymphony.com/secure/ReleaseNote.jspa?projectId=10050&styleName=Html&version=21701 Vendor Advisory
http://jira.opensymphony.com/secure/ReleaseNote.jspa?projectId=10050&styleName=Html&version=21706 Vendor Advisory
http://osvdb.org/37072 Broken Link
http://secunia.com/advisories/26681 Third Party Advisory
http://secunia.com/advisories/26693 Third Party Advisory
http://secunia.com/advisories/26694 Third Party Advisory
http://struts.apache.org/2.x/docs/s2-001.html Patch Third Party Advisory
http://wiki.opensymphony.com/display/WW/1.2.3+Press+Release Vendor Advisory
http://www.securityfocus.com/bid/25524 Third Party Advisory VDB Entry
http://www.vupen.com/english/advisories/2007/3041 Third Party Advisory
http://www.vupen.com/english/advisories/2007/3042 Third Party Advisory
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