CVE-2026-59884: high-severity vulnerability in pyasn1
pyasn1 BER/CER/DER decoder denial of service via unbounded long-form tag IDs
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.6%
pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
pyasn1 · pyasn1Related CVEs — pyasn1
In the same product, most dangerous first.
CVE-2026-30922HIGHpyasn1 Vulnerable to Denial of Service via Unbounded RecursionEPSS 0.8%CVE-2026-23490HIGHpyasn1 has a DoS vulnerability in decoderEPSS 0.8%CVE-2026-59885HIGHpyasn1: Quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows denial of serviceEPSS 0.6%CVE-2026-119195HIGHpyasn1: Quadratic-time denial of service in constructed string and indefinite-length ANY decodingEPSS 0.5%CVE-2026-59886HIGHpyasn1: Uncontrolled resource consumption when converting decoded REAL valuesEPSS 0.4%CVE-2026-119197HIGHpyasn1: Quadratic-complexity denial of service in binary REAL decodingEPSS 0.4%