CVE-2022-34476 in Firefox
Summary
by MITRE • 12/22/2022
ASN.1 parsing of an indefinite SEQUENCE inside an indefinite GROUP could have resulted in the parser accepting malformed ASN.1. This vulnerability affects Firefox < 102.
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Analysis
by VulDB Data Team • 04/16/2025
The vulnerability identified as CVE-2022-34476 represents a critical flaw in the ASN.1 parsing implementation within Mozilla Firefox browsers version 102 and earlier. This issue stems from the improper handling of indefinite-length ASN.1 structures, specifically when an indefinite SEQUENCE is nested within an indefinite GROUP. The fundamental problem lies in the parser's inability to correctly validate the structure and boundaries of these nested indefinite constructs, leading to potential acceptance of malformed ASN.1 data that should have been rejected during the parsing process.
The technical flaw manifests in the ASN.1 parser's state management and boundary checking mechanisms when processing indefinite-length encodings. According to the Common Weakness Enumeration framework, this vulnerability maps to CWE-129, which describes improper validation of array index values, though in this case the weakness extends to improper validation of ASN.1 structure boundaries. The parser fails to properly track the nesting levels and length indicators when encountering indefinite SEQUENCE within indefinite GROUP constructs, creating a potential path for malformed data to be accepted and processed incorrectly. This type of vulnerability falls under the ATT&CK technique T1203, which involves exploiting software vulnerabilities to gain unauthorized access to systems.
The operational impact of this vulnerability extends beyond simple parsing errors, as it could potentially enable attackers to craft malicious ASN.1 structures that bypass security checks and validation mechanisms. When Firefox processes certificates, cryptographic messages, or other ASN.1-encoded data, the parser's failure to properly validate nested indefinite structures could allow attackers to inject malformed data that appears valid to the parser but contains unexpected behavior. This vulnerability particularly affects the browser's handling of X.509 certificates and other cryptographic protocols that rely heavily on ASN.1 encoding, potentially creating opportunities for man-in-the-middle attacks or certificate validation bypasses. The security implications are significant as it undermines the integrity of the browser's cryptographic processing pipeline and could lead to trust validation failures.
Mitigation strategies for CVE-2022-34476 primarily focus on updating Firefox to version 102 or later, where the ASN.1 parsing logic has been corrected to properly handle indefinite-length structures. Organizations should prioritize immediate patching of affected systems and implement monitoring for any suspicious certificate validation activities or unexpected behavior in cryptographic operations. The fix typically involves strengthening the parser's boundary checking mechanisms and ensuring proper state tracking when processing nested indefinite ASN.1 constructs. Security teams should also consider implementing additional validation layers for ASN.1 data processing and monitor network traffic for potential exploitation attempts targeting this specific parsing vulnerability. Regular security assessments of cryptographic libraries and browser configurations remain essential to prevent similar issues in other software components that may utilize ASN.1 parsing functionality.