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CVE-2026-30922 high CVSS 7.5

Vulnerability in pyasn1 (CVE-2026-30922)

Summary

Vulnerability in pyasn1 (CVE-2026-30922). Risk of unauthorized operations or information disclosure. Exploitable via pyasn1. Mitigation: upgrade to 0.6.3 or later.

Original description

The description as published by the source.

Summary

The pyasn1 library is vulnerable to a Denial of Service (DoS) attack caused by uncontrolled recursion when decoding ASN.1 data with deeply nested structures. An attacker can supply a crafted payload containing nested SEQUENCE (0x30) or SET (0x31) tags with Indefinite Length (0x80) markers. This forces the decoder to recursively call itself until the Python interpreter crashes with a RecursionError or consumes all available memory (OOM), crashing the host application.

Details

The vulnerability exists because the decoder iterates through the input stream and recursively calls decodeFun (the decoding callback) for every nested component found, without tracking or limiting the recursion depth.
Vulnerable Code Locations:

  1. indefLenValueDecoder (Line 998):
    for component in decodeFun(substrate, asn1Spec, allowEoo=True, **options):
    This method handles indefinite-length constructed types. It sits inside a while True loop and recursively calls the decoder for every nested tag.

  2. valueDecoder (Lines 786 and 907):
    for component in decodeFun(substrate, componentType, **options):
    This method handles standard decoding when a schema is present. It contains two distinct recursive calls that lack depth checks: Line 786: Recursively decodes components of SEQUENCE or SET types. Line 907: Recursively decodes elements of SEQUENCE OF or SET OF types.

  3. _decodeComponentsSchemaless (Line 661):

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

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-2026-30922 has been found in pyasn1.
Attackers can target a specific entry point like pyasn1 over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade pyasn1 to 0.6.3 or later.
If unsure, ask your IT team or search "pyasn1 CVE-2026-30922" on the vendor's site.

CVE-2026-30922 (pyasn1) — CWE-674 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: pyasn1 / SEQUENCE / SET / RecursionError
Patched: 0.6.3 — 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.

❓ What is the problem

A vulnerability (CWE-674) exists in pyasn1. Attackers reach the vulnerable code path via pyasn1 without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of pyasn1. Attack surface: pyasn1 / SEQUENCE / SET / RecursionError.

🔥 Severity

Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 0.6.3.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

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

  1. 1
    Identify 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。

  2. 2
    Apply patch patch 
    Upgrade pyasn1 to 0.6.3

    ステージング環境で 0.6.3 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。

  3. 3
    Post-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

PyPI pyasn1
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.6.3"}]}]
pip pyasn1
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.6.3"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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