VulnerabilityPublished 11 Nov 2026

CVE-2026-62971: coreruleset · Improper Neutralization of Special Elements

Affects corerulesetSource CVE Database V5

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Not known to be exploited · CVSS 7.2 High · fixed in 4.28.0 : patch coreruleset soon.

Data as of 11 Nov 2026, 17:35 UTC

CVSS 3.1 base score

7.2High

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	7.2

Patch: Available – fixed in 4.28.0, 4.25.1, 3.3.10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Changed
Confidentiality: Low
Integrity: Low
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade coreruleset to 4.28.0, 4.25.1 or 3.3.10.

Affected software

Product	Affected	Fixed in
corerulesetcoreruleset	Affected <4.28.0	Fixed in 4.28.0
corerulesetcoreruleset	Affected <4.25.1	Fixed in 4.25.1
corerulesetcoreruleset	Affected <3.3.10	Fixed in 3.3.10

AI-suggested

Upgrade to OWASP CRS version 3.3.10, 4.25.1, or 4.28.0 or later, where this vulnerability is patched. These versions include fixes that properly inspect XML attribute values in addition to element text nodes, closing the bypass. No additional mitigation is required once the CRS is updated to a fixed version.

Description

CVE-2026-62971 is a vulnerability in the OWASP core rule set (CRS) affecting versions prior to 3.3.10, 4.25.1, and 4.28.0. The issue involves improper neutralization of special elements in XML request bodies, where CRS rules inspect only element text nodes but not XML attribute values. This allows attackers to bypass detection by placing malicious payloads inside XML attributes. The vulnerability affects approximately 159 rules across nine rule files and applies to all paranoia levels except the 944 (Java) family, which is unaffected. The issue has been patched in the specified fixed versions.

Impact

An attacker can bypass OWASP CRS detection by embedding attack payloads inside XML attribute values, evading detection by approximately 159 rules across nine rule files. This bypass affects all paranoia levels except the 944 (Java) family. The vulnerability could allow malicious payloads such as cross-site scripting (XSS), SQL injection (SQLi), remote code execution (RCE), and other protocol attacks to go undetected by the CRS, potentially compromising web application firewall protections.

CWE-138Improper Neutralization of Special Elements (opens in a new tab)
Class weaknessOWASP Top 10 A03:2021: Injection (opens in a new tab)
The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as control elements or syntactic markers when they are sent to a downstream component.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Implementation
Developers should anticipate that special elements (e.g. delimiters, symbols) will be injected into input vectors of their product. One defense is to create an allowlist (e.g. a regular expression) that defines valid input according to the requirements specifications.
Implementation · Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
Implementation
Use and specify an appropriate output encoding to ensure that the special elements are well-defined. A normal byte sequence in one encoding could be a special element in another.
OWASP Cheat Sheets
Server Side Request Forgery Prevention (opens in a new tab)
Unvalidated Redirects and Forwards (opens in a new tab)
Cross Site Scripting Prevention (opens in a new tab)
DOM based XSS Prevention (opens in a new tab)
Abuse Case (opens in a new tab)
OWASP ASVS 4.0.3
V5.2.2 (opens in a new tab)
V1.5.1 (opens in a new tab)
Attack patterns
HTTP Request Splitting (opens in a new tab)
Command Delimiters (opens in a new tab)
HTTP Response Splitting (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Nov 2026, 17:35 UTC

WeaknessesCWE-138

Technical details

References

Community reviews

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