vulnerability / NVI-00009211 / Revision 3
pyasn1 has quadratic-time denial of service in constructed string and indefinite-length ANY decoding
GitHub lists this reviewed advisory for pyasn1. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
7.5 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
7.5 HIGH (3.1)
security-advisories@github.com severity; no combined Null risk score.
0.527%
FIRST EPSS model v2026.06.15; exploitation probability over 30 days, percentile 0.44645. Missing scores are unknown.
As of · FIRST EPSS
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
pyasn1
source listed<= 0.6.4
## Summary In pyasn1 0.6.4 and earlier, decoding a constructed OCTET STRING or character string made of many fragments can spend disproportionate CPU time repeatedly copying the accumulated value. A separate indefinite-length `ANY` path has the same problem while collecting the encoded components. The work grows roughly quadratically with the number of fixed-size fragments, although the input and decoded value grow linearly. An application that lets an attacker supply such ASN.1 input to an affected decoder can suffer CPU exhaustion. The affected string paths are available in BER and CER. The DER decoder also accepts certain *non-DER* constructed strings: a definite-length constructed OCTET STRING when an `asn1Spec` selects `univ.OctetString`, and constructed character strings such as UTF8String even without a schema. Indefinite-length `ANY` is affected in BER and CER when an `asn1Spec` selects `univ.Any`; DER rejects indefinite lengths. This is a distinct decoder path from the OBJECT IDENTIFIER/RELATIVE-OID accumulation addressed by CVE-2026-59885. It has the same complexity class, but the OID fix in 0.6.4 did not change thes
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. FIRST EPSS
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
- NVD lastModified does not establish freshness of every associated CPE record.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-9m75-vc3g-4x39 ↗
GitHub Advisory Database · vendor advisory
Observed . GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.
- CVE-2026-119195 ↗
NIST National Vulnerability Database · official catalog
Observed . This product uses data from the NVD API but is not endorsed or certified by the NVD.
- CVE-2026-119195 ↗
FIRST EPSS · official catalog
Observed . FIRST EPSS; probability of exploitation in the next 30 days, not local compromise. Dataset date/model retained; FIRST services terms apply.
Public revision history
Only published revisions appear here. Routine fetches do not create a material-change event.
- Revision 3 ·
Source facts changed; compare the preserved prior revision.
- Revision 2 ·
Dated EPSS estimate updated; this is not a new disclosure or proof of exploitation.
- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.