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CVE-2026-48156 low CVSS 3.3

Vulnerability in pypdf (CVE-2026-48156)

Summary

Vulnerability in pypdf (CVE-2026-48156). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 6.12.0 or later.

Original description

The description as published by the source.

Impact

An attacker who uses this vulnerability can craft a PDF which leads to long runtimes. This requires cross-reference streams with /W [0 0 0] values and large /Size values.

Patches

This has been fixed in pypdf==6.12.0.

Workarounds

If developers are unable to upgrade their apps immediately, they should consider applying the changes from PR #3791.

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-2026-48156 has been found in pypdf.
Risk of unauthorized operations or information disclosure. CVSS score: 3.3/10.
What to do: upgrade pypdf to 6.12.0 or later.
If unsure, ask your IT team or search "pypdf CVE-2026-48156" on the vendor's site.

CVE-2026-48156 (pypdf) — CWE-834 / CVSS v3 3.3
Attack vector: local / unauthenticated
Patched: 6.12.0 — apply immediately
Workaround: If developers are unable to upgrade their apps immediately, they should consider applying the changes from PR #3791.
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-834) exists in pypdf.

📍 Affected scope

Check the vendor advisory for the affected versions of pypdf.

🔥 Severity

Severity: Low (CVSS 3.3/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 6.12.0.

🛡️ Workaround

Workaround: If developers are unable to upgrade their apps immediately, they should consider applying the changes from PR #3791.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'pypdf' . 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 'pypdf' . | 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 pypdf 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 temporary workaround mitigate 
    If developers are unable to upgrade their apps immediately, they should consider applying the changes from PR [#3791](https://github.com/py-pdf/pypdf/pull/3791).

    パッチが適用されるまでの応急処置として、If developers are unable to upgrade their apps immediately, they should consider applying the changes from PR #3791. を実施。回避策の副作用 (機能低下) を確認した上で。

  3. 3
    Apply patch patch 
    Upgrade pypdf to 6.12.0

    ステージング環境で 6.12.0 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。

  4. 4
    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

pip pypdf
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.0"}]}]
PyPI pypdf
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.0"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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