VulnerabilityPublished 24 Apr 2023Updated 30 May 2025

CVE-2023-28484: libxml2 · NULL Pointer Dereference

Source CVE Database V5

Not known to be exploited · CVSS 6.5 Medium : upgrade to 2.10.4 when convenient.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

6.5Medium

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

EPSS: 1.2% chance of exploitation in 30 days – higher than 69% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 2.10.4

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

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

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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 24 Apr 2023
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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 the Debian debian/libxml2 package to 2.10.4.

Affected software

Product	Affected	Fixed in
Debiandebian/libxml2`pkg:deb/debian/libxml2`Other threats	Affected <2.10.4	Fixed in 2.10.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2023-28484, European organizations should: 1) Upgrade libxml2 to version 2.10.4 or later, where the vulnerability has been addressed. 2) Implement strict input validation and sanitization for all XML and XSD files processed by applications, rejecting malformed or suspicious schemas before parsing. 3) Employ application-level sandboxing or process isolation for XML parsing components to contain crashes and prevent wider system impact. 4) Educate users about the risks of opening untrusted XML or XSD files, especially from external sources, to reduce the likelihood of user interaction-based exploitation. 5) Monitor application logs and system behavior for signs of crashes or abnormal terminations related to XML processing. 6) Where possible, configure XML parsers to operate in safe modes or with reduced privileges to limit the impact of potential crashes. 7) Maintain an inventory of software and services using libxml2 to prioritize patching and risk assessment. These steps go beyond generic advice by focusing on proactive input validation, user awareness, and architectural controls to reduce both the likelihood and impact of exploitation.

Description

In libxml2 before 2.10.4, parsing of certain invalid XSD schemas can lead to a NULL pointer dereference and subsequently a segfault. This occurs in xmlSchemaFixupComplexType in xmlschemas.c.

Impact

For European organizations, the primary impact of CVE-2023-28484 is the potential for denial of service in systems that rely on libxml2 for XML schema validation. This could affect a wide range of applications including web servers, middleware, enterprise software, and security tools that parse XML schemas. Disruptions could lead to temporary service outages, impacting business continuity and operational efficiency. Although the vulnerability does not compromise confidentiality or integrity, availability impacts can be critical in sectors such as finance, healthcare, telecommunications, and government services where XML-based data exchange and validation are common. Additionally, user interaction is required for exploitation, which somewhat limits the attack surface but does not eliminate risk, especially in environments where users handle XML files regularly. The absence of known exploits reduces immediate risk but does not preclude future exploitation attempts. Organizations using outdated libxml2 versions should be aware that attackers could craft malicious XSD files to trigger crashes, potentially as part of a broader attack or disruption campaign.

CWE-476NULL Pointer Dereference (opens in a new tab)
Base weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #13OWASP Top 10 A10:2025: Mishandling of Exceptional Conditions (opens in a new tab)
The product dereferences a pointer that it expects to be valid but is NULL.
Implementation
For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
Requirements
Select a programming language that is not susceptible to these issues.
Implementation
Check the results of all functions that return a value and verify that the value is non-null before acting upon it.
OWASP Cheat Sheets
Logging (opens in a new tab)
Error Handling (opens in a new tab)
OWASP ASVS 4.0.3
V11.1.7 (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 8 Jul 2025, 13:58 UTC

WeaknessesCWE-476

Technical details

References

Community reviews

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