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CVE-2026-62971 OWASP CRS: XML Attribute Value Bypass

7.2 highEPSS 0.4%

High (7.2) in coreruleset coreruleset. EPSS 0.4% estimated probability of exploitation activity in the next 30 days.

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The OWASP core rule set (CRS) is a set of generic attack detection rules for use with compatible web application firewalls. Prior to versions 3.3.10, 4.25.1, and 4.28.0, CRS rules in the 921 (protocol-attack), 930 (LFI), 931 (RFI), 932 (RCE), 933 (PHP), 934 (generic), 941 (XSS), 942 (SQLi), and 943 (session-fixation) families inspect XML request bodies via the XPath expression XML:/*. That expression matches only element text nodes — it does not match XML attribute values. As a result, an attacker who places an attack payload inside an XML attribute (e.g. <a href="javascript:alert(1)=window.name"></a> or <a value="' OR 1=1 --"></a>) bypasses CRS detection entirely. This is verified empirically against a local CRS test instance and against the public CRS sandbox. The bypass affects approximately 159 rules across 9 rule files and applies at every paranoia level (PL1 through PL4), since the variable list is more or less shared across PLs. The 944 (Java) family is the only one that correctly includes XML://@* in addition to XML:/* and is therefore unaffected. This issue has been patched in versions 3.3.10, 4.25.1, and 4.28.0.

Severity

CVSS 3.1

7.2 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
EPSS
0.4% estimated probability of exploitation activity in the next 30 days; 37th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
CWE
CWE-138 Improper Neutralization of Special Elements
Published
Modified
Assigned by
GitHub_M (CNA)
NVD analysis
Awaiting analysis
Record from
the NVD, synced

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Affected

Versions

From the CNA's record in the CVE List.

ProductAffected
coreruleset< 3.3.10
coreruleset< 4.25.1
coreruleset< 4.28.0

Linux distributions

DistributionReleasePackageFixed inAdvisory
Debian12, 13, 14modsecurity-crsno fix listedDEBIAN-CVE-2026-62971

From the distributions' data via OSV.dev: the Debian Security Tracker. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Debian.

Attack patterns (CAPEC)

  • CAPEC-15 Command Delimiters Likelihood: High · Severity: High
  • CAPEC-34 HTTP Response Splitting Likelihood: Medium · Severity: High
  • CAPEC-105 HTTP Request Splitting Likelihood: Medium · Severity: High

The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.

References

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