Vulnerability in pyasn1 (CVE-2026-59886)
Summary
Vulnerability in pyasn1 (CVE-2026-59886). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 0.6.4 or later.
Original description
The description as published by the source.
pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the univ.Real type converted its mantissa, base, and exponent value to a Python float using exact big-integer exponentiation. A BER, CER, or DER encoded REAL value only a few bytes long can carry a very large exponent, causing float conversion through prettyPrint(), str(), comparison, arithmetic, int(), or an explicit float() call to consume excessive CPU and memory and hang applications that decode untrusted ASN.1 data and then print, log, or compare decoded objects. This issue is fixed in version 0.6.4.
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-59886 has been found in pyasn1.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade pyasn1 to 0.6.4 or later.
If unsure, ask your IT team or search "pyasn1 CVE-2026-59886" on the vendor's site.
CVE-2026-59886 (pyasn1) — CWE-400 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 0.6.4 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-400) exists in pyasn1.
Check the vendor advisory for the affected versions of pyasn1.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 0.6.4.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'pyasn1' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'pyasn1' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
pyasn1を grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade pyasn1 to 0.6.4ステージング環境で 0.6.4 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- BellSoft Alpaquita BELL-CVE-2026-59886 py3-asn1 Fixed in: 0.4.8-r6
- Ubuntu UBUNTU-CVE-2026-59886 pyasn1
References
- advisory github.com
- advisory github.com
- patch github.com
- web nvd.nist.gov
- web github.com