← Back
CVE-2026-59884
high
CVSS 7.5
Vulnerability in pyssn1 (CVE-2026-59884)
Summary
vulnerability in pyssn1 (CVE-2026-59884). Risk of unauthorized operations or information disclosure. Exploitable via ``ValueError``. Mitigation: upgrade to `0.6.4` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-59884** has been found in pyssn1.
Attackers can target a specific entry point like ``ValueError`` over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade pyssn1 to **0.6.4** or later.
If unsure, ask your IT team or search "pyssn1 CVE-2026-59884" on the vendor's site.
CVE-2026-59884 (pyssn1) — CWE-400 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: `ValueError` / `PyAsn1Error` / `pyasn1.codec.ber.decoder` / `StreamingDecoder`
Patched: `0.6.4` — apply immediately
Workaround: Bound the size of untrusted input passed to `decode()` before calling it.
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.
❓ What is the problem
**A vulnerability** (CWE-400) exists in pyssn1. Attackers reach the vulnerable code path via ``ValueError`` without authentication.
📍 Affected scope
pyssn1 — . Attack surface: `ValueError` / `PyAsn1Error` / `pyasn1.codec.ber.decoder` / `StreamingDecoder`.
🔥 Severity
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure
🔧 How to fix
Update to **0.6.4**.
🛡️ Workaround
Workaround: Bound the size of untrusted input passed to `decode()` before calling it.
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'pyssn1' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response Actions (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'pyssn1' . | 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 `pyssn1` を grep し、稼働しているサービス・バージョンを把握する。
-
5Apply temporary workaround mitigate
Bound the size of untrusted input passed to `decode()` before calling it.パッチが適用されるまでの応急処置として、Bound the size of untrusted input passed to `decode()` before calling it. を実施。回避策の副作用 (機能低下) を確認した上で。
-
6Apply patch patch
Upgrade pyssn1 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と、Step 3 で見つけた異常検知の続報チェックを含めること。
-
7Post-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 Step 3 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
pip
pyssn1
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.6.4"}]}]
pip
pyasn1
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.6.4"}]}]
References
- web https://github.com/pyasn1/pyasn1/commit/628e36ecbb5277a3f01572ce418ef54271b165a5
- web https://github.com/pyasn1/pyasn1/releases/tag/v0.6.4
- web https://github.com/pyasn1/pyasn1/security/advisories/GHSA-m4p7-r5rc-7g4j
- web https://nvd.nist.gov/vuln/detail/CVE-2026-59884
- web https://github.com/advisories/GHSA-m4p7-r5rc-7g4j
- web https://github.com/pypa/advisory-database/tree/main/vulns/pyasn1/PYSEC-2026-3455.yaml