CVE-2026-119195 pyasn1: Quadratic-time denial of service in constructed string and indefinite-length ANY decoding
- Exploited in the wild
- Not known
- Fix
- None listed
What is CVE-2026-119195?
CVE-2026-119195 is a high-severity vulnerability in pyasn1, published on 29 Oct 2026.
Official description
pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.5, constructed string and indefinite-length ANY decoding repeatedly concatenates each fragment onto a growing bytes value. Attacker-controlled BER or CER data can use many constructed OCTET STRING or character-string fragments. DER rejects constructed OCTET STRING without a schema, but accepts its definite-length form when asn1Spec selects univ.OctetString; it also accepts constructed character strings such as UTF8String without a schema, even though those encodings are not valid DER. The separate indefinite-length ANY path is reachable in BER and CER when asn1Spec selects univ.Any; DER rejects indefinite lengths. OctetStringPayloadDecoder uses growing header concatenation and AnyPayloadDecoder.indefLenValueDecoder uses growing chunk concatenation, repeatedly copying an increasing prefix and causing quadratic work. A sufficiently fragmented value can occupy decoding workers and cause CPU exhaustion without confidentiality or integrity impact. This issue is fixed in version 0.6.5.
Weakness: CWE-407
Which versions are affected by CVE-2026-119195?
How do I fix CVE-2026-119195?
No fix has been published for CVE-2026-119195 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-119195 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-119195 exists.