pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER, CER, and DER decoders process OBJECT IDENTIFIER and RELATIVE-OID values in quadratic time relative to the number of arcs, so a small crafted payload containing an OID with many arcs consumes excessive CPU per decode() call and can deny service to applications that decode untrusted ASN.1 data. The corresponding encoders have the same quadratic behavior when an application re-encodes previously decoded attacker-supplied values. This issue is fixed in version 0.6.4.
CVE-2026-59885
This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 74% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EPSS
- 26.3%
- KEV
- Not listed
Published
July 14, 2026
Last Modified
July 21, 2026
Advisory Details (3)
Auto-updated Jul 15, 2026Quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows denial of service · Advisory · pyasn1/pyasn1 · GitHub
https://github.com/pyasn1/pyasn1/security/advisories/GHSA-8ppf-4f7h-5ppjRelease 0.6.4
Patch available: pyasn1/pyasn1 v0.6.4
https://github.com/pyasn1/pyasn1/releases/tag/v0.6.4commit 45bdb19eb7df (pyasn1/pyasn1)
Patch available: pyasn1/pyasn1 v0.6.4 (contains commit 45bdb19eb7df)
https://github.com/pyasn1/pyasn1/commit/45bdb19eb7df4b3780fe9c912c63e99bffc39dd9Vendor Advisories for CVE-2026-59885(2)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- GHSA-8ppf-4f7h-5ppjGitHub Security AdvisoriesHigh
pyasn1: Quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows denial of service
- CVE-2026-59885Microsoft Security Response Center (MSRC)High
pyasn1: Quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows denial of service
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 13× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-22 14:08 UTCEPSS rescore
- 2026-07-22 14:08 UTCEPSS rescore
- 2026-07-21 15:25 UTCEPSS rescore
- 2026-07-21 15:25 UTCEPSS rescore
- 2026-07-20 17:08 UTCEPSS rescore
- 2026-07-19 14:31 UTCEPSS rescore
- 2026-07-19 02:29 UTCEPSS rescore
- 2026-07-18 10:04 UTCEPSS rescore
- 2026-07-16 17:03 UTCEPSS rescore
- 2026-07-15 16:57 UTCEPSS rescore
- 2026-07-15 16:57 UTCEPSS rescore
- 2026-07-14 17:16 UTCEG score recompute
- 2026-07-14 17:10 UTCMITRE cvelistV5first tracked
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Same CWE
10 shownCWE-400
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Dependency Blast Radius
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