High · CVSS 7.5CVE-2026-119195

pyasn1: Quadratic-time denial of service in constructed string and indefinite-length ANY decodingCVE-2026-119195

Answer in brief

CVE-2026-119195 records a High severity (CVSS 7.5) vulnerability in pyasn1: Quadratic-time denial of service in constructed string and indefinite-length ANY decoding. The current sources do not mark it as known exploited. The current feed maps pyasn1/pyasn1 (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Oct 29, 2026Updated Oct 29, 2026Source checked Oct 29, 2026First seen by HOL Oct 29, 2026Material review Oct 29, 2026

Upstream Advisory

Key facts

Risk: High · CVSS 7.5
Exploitation: Not marked as known exploited
Affected software: 1 mapped package or product
Fix availability: Available

Why this deserves its current priority

CVSS is 7.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps pyasn1/pyasn1 (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
pyasn1/pyasn1generic	<0.6.5	0.6.5

Recommended response

Check inventory. Check lockfiles and deployed manifests for pyasn1/pyasn1.
Review the reported fix. Update pyasn1/pyasn1 to 0.6.5 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Oct 29, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Oct 29, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Oct 29, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.