VulnerabilityPublished 24 Oct 2022Updated 30 May 2025

CVE-2022-43680: libexpat · Use After Free

Source CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 15:59 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 3.1% chance of exploitation in 30 days – higher than 87% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
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: None: The vulnerable system can be exploited without any interaction from any user.
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 Oct 2022
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

Affected software

Product	Affected	Fixed in
GitHublibexpat/libexpat`pkg:github/libexpat/libexpat`Other threats	Affected <=2.4.9	Fixed in–

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-2022-43680, European organizations should: 1) Identify all software and systems that incorporate libexpat, especially versions up to 2.4.9. 2) Monitor vendor advisories for patches or updates that address this vulnerability and apply them promptly. 3) Where direct patching of libexpat is not feasible (e.g., embedded devices), consider applying compensating controls such as limiting exposure of affected services to untrusted networks via network segmentation and firewall rules. 4) Implement robust resource monitoring and memory management safeguards to detect and respond to out-of-memory conditions that could trigger the vulnerability. 5) Conduct thorough testing of XML processing components under stress conditions to identify potential instability. 6) Employ runtime protections such as AddressSanitizer or similar memory error detection tools during development and testing phases to catch use-after-free issues early. 7) Maintain up-to-date incident response plans to quickly address potential denial-of-service incidents stemming from this vulnerability.

Description

In libexpat through 2.4.9, there is a use-after free caused by overeager destruction of a shared DTD in XML_ExternalEntityParserCreate in out-of-memory situations.

Impact

For European organizations, the primary impact of CVE-2022-43680 is the potential for denial-of-service (DoS) conditions in applications or services that rely on libexpat for XML parsing. This can lead to service outages, degraded performance, or application crashes, affecting business continuity and availability of critical systems. Industries that heavily utilize XML processing—such as telecommunications, finance, government services, and industrial control systems—may be particularly vulnerable. While the vulnerability does not directly compromise confidentiality or integrity, the induced DoS could disrupt operations or be leveraged as part of a broader attack chain. Given the remote exploitability without authentication or user interaction, attackers could trigger this vulnerability over the network, increasing the risk profile. European organizations with legacy systems or embedded devices using older libexpat versions may face higher exposure. The absence of known exploits in the wild reduces immediate risk but does not eliminate the need for proactive mitigation.

Summary

CVE-2022-43680 is a high-severity vulnerability identified in libexpat, a widely used XML parsing library. The issue is a use-after-free (CWE-416) vulnerability that occurs due to the premature destruction of a shared Document Type Definition (DTD) object within the function XML_ExternalEntityParserCreate when the system encounters out-of-memory conditions. Specifically, when libexpat attempts to create an external entity parser and runs out of memory, it erroneously frees a shared DTD resource too eagerly, leading to a use-after-free scenario. This type of vulnerability can cause the program to access memory that has already been freed, potentially resulting in application crashes or undefined behavior. According to the CVSS v3.1 vector (7.5), the vulnerability can be exploited remotely without authentication or user interaction, and it impacts availability (denial of service) but not confidentiality or integrity. No known exploits are currently reported in the wild, and no vendor or product specifics are provided, but libexpat is commonly embedded in many software products and systems that process XML data. The lack of patch links suggests that remediation may require updating libexpat to a fixed version beyond 2.4.9 once available or applying vendor-specific patches if libexpat is bundled within other software.

CWE-416Use After Free (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #7
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Architecture and Design · Language Selection
Choose a language that provides automatic memory management.
Implementation · Attack Surface Reduction
When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (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, 14:12 UTC

WeaknessesCWE-416

Technical details

References

Community reviews

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