constructed string · pyasn1: Quadratic-time denial of service
Affects MicrosoftSource GCVE Database
Not known to be exploited · CVSS 7.5 High : upgrade to 0.6.5 soon.
Data as of 31 Oct 2026, 08:50 UTC
Thin evidence
One scorer or none| CNA (GitHub_M) | CVSS 3.1 | 7.5 |
|---|
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 0.6.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 29 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade pyasn1 to 0.6.5.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| pyasn1pyasn1 | Affected
| Fixed in
|
PyPIpyasn1pkg:pypi/pyasn1Other threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
If you cannot patch yet, consider limiting exposure to untrusted ASN.1 data or applying application-level resource constraints.
Description
A vulnerability in pyasn1 version 3.0 allows a quadratic-time denial of service during constructed string and indefinite-length ANY decoding. This flaw can cause excessive resource consumption leading to denial of service conditions.