Expat up to 2.8.4 xml injection

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.3$0-$5k6.03

Summaryinfo

A vulnerability classified as problematic was found in Expat up to 2.8.4. This impacts an unknown function. The manipulation results in xml injection. This vulnerability was named CVE-2026-93990. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability classified as problematic has been found in Expat up to 2.8.4. Affected is an unknown function. The manipulation with an unknown input leads to a xml injection vulnerability. CWE is classifying the issue as CWE-91. The product does not properly neutralize special elements that are used in XML, allowing attackers to modify the syntax, content, or commands of the XML before it is processed by an end system. This is going to have an impact on integrity. CVE summarizes:

Expat through 2.8.4 fails to validate low surrogates following high surrogates in UTF-16 input, allowing malformed UTF-16 sequences to be accepted. Attackers can craft UTF-16 encoded XML with lone high surrogates that consume following code units, hiding markup characters from the parser and enabling XML injection attacks.

The advisory is shared for download at github.com. This vulnerability is traded as CVE-2026-93990 since 09/19/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 09/20/2026). The MITRE ATT&CK project declares the attack technique as T1505.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 6.4
VulDB Meta Temp Score: 6.3

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector (VulnCheck): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Xml injection
CWE: CWE-91 / CWE-74 / CWE-707
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

09/19/2026 CVE reserved
09/19/2026 +0 days VulDB entry created
09/20/2026 +0 days Advisory disclosed
09/20/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Not defined

CVE: CVE-2026-93990 (🔒)
GCVE (CVE): GCVE-0-2026-93990
GCVE (VulDB): GCVE-100-407988

Entryinfo

Created: 09/20/2026 01:18
Changes: 09/20/2026 01:18 (72)
Complete: 🔍
Cache ID: 216::103

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