CVE-2026-30922High· 7.5▾ MidnightPoC availablepyasn1 is a generic ASN.1 library for Python. Prior to 0.6.3, the `pyasn1` library is vulnerable to a Denial of Service (DoS) attack caused by uncontrolled recursion when decoding ASN.1 data with deeply nested structures. An attacker can…
▾ Midnight zone — Critical, or high with PoC / in-the-wild
impact 41.3 · likelihood 0.2 · exploitation 12
A public proof-of-concept already exists for this vulnerability — see Exploit availability below.
Stakeholder-Specific Vulnerability Categorization from CISA's ADP record at CVE.org: whether exploitation is observed, whether an attack can be automated, and how much of the system is at stake. The CVSS score shown above comes from the assigning CNA record, not NVD.
Exploit-prediction probability, daily snapshots since Jul 13.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via CVEORG
0.6%
0.6% → 0.8%
Exploit / PoC code exists
Last analysed / modified upstream
pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.3, the pyasn1 library is vulnerable to a Denial of Service (DoS) attack caused by uncontrolled recursion when decoding ASN.1 data with deeply nested structures. An attacker can supply a crafted payload containing thousands of nested SEQUENCE (0x30) or SET (0x31) tags with "Indefinite Length" (0x80) markers. This forces the decoder to recursively call itself until the Python interpreter crashes with a RecursionError or consumes all available memory (OOM), crashing the host application. This is a distinct vulnerability from CVE-2026-23490 (which addressed integer overflows in OID decoding). The fix for CVE-2026-23490 (MAX_OID_ARC_CONTINUATION_OCTETS) does not mitigate this recursion issue. Version 0.6.3 fixes this specific issue.
pyasn1 < 0.6.3Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Affected packages:
pyasn1 < 0.6.3Patched in:
pyasn1 0.6.3Source: https://osv.dev/vulnerability/GHSA-jr27-m4p2-rc6r
Field changes observed since this record was first indexed.
Connected by shared product, vendor, weakness, or advisory.
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