CVE-2018-20843
HighCVSS 7.5Exploitation Probability (EPSS)
Very high risk94th percentile - higher than 94% of all known CVEs
Summary
In libexpat (Expat before 2.2.7), XML input including XML names with a large number of colons could make the parser consume high amounts of RAM and CPU resources, enough for denial-of-service attacks.
Risk Assessment
An attacker can send a specially crafted XML document, causing excessive resource consumption and denial of service for applications using Expat.
Recommendation
Update Expat to version 2.2.7 or later. Limit processing of untrusted XML documents.
Other vulnerabilities in Expat
See all- CVE-2022-25315Critical
In Expat (aka libexpat) before 2.4.5, there is an integer overflow in storeRawNames.
- CVE-2022-25314High
In Expat (libexpat) before 2.4.5, there is an integer overflow in copyString.
- CVE-2022-25236Critical
In xmlparse.c in Expat (aka libexpat) before 2.4.5, attackers can insert namespace-separator characters into namespace URIs.
- CVE-2022-25235Critical
In xmltok_impl.c in Expat (aka libexpat) before 2.4.5 lacks certain validation of encoding, such as checks for whether a UTF-8 character is valid in a certain context.
- CVE-2022-23990High
Expat (libexpat) before 2.4.4 has an integer overflow in the doProlog function. This may lead to improper XML parser behavior.
- CVE-2022-23852Critical
Expat (aka libexpat) before 2.4.4 has a signed integer overflow in XML_GetBuffer, for configurations with a nonzero XML_CONTEXT_BYTES.
- CVE-2022-22824Critical
The defineAttribute function in xmlparse.c in Expat (libexpat) before 2.4.3 has an integer overflow. This may lead to incorrect behavior of the XML parser.
- CVE-2022-22823Critical
The build_model function in xmlparse.c in Expat (libexpat) before 2.4.3 has an integer overflow. This may lead to incorrect behavior of the XML parser.
- CVE-2022-22822Critical
addBinding in xmlparse.c in Expat (aka libexpat) before 2.4.3 has an integer overflow.
- CVE-2021-45960High
In Expat (libexpat) before 2.4.3, a left shift by 29 or more bits in the storeAtts function in xmlparse.c can lead to realloc misbehavior, such as allocating too few bytes or only freeing memory.
Original NVD description (English source)
In libexpat in Expat before 2.2.7, XML input including XML names that contain a large number of colons could make the XML parser consume a high amount of RAM and CPU resources while processing (enough to be usable for denial-of-service attacks).
Vulnerability data from NVD (NIST) · CISA KEV · EPSS