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CVE-2026-6100 high CVSS 8.1

Use-After-Free in python (CVE-2026-6100)

Summary

Vulnerability in python (CVE-2026-6100). Successful exploitation can lead to full system takeover. Exploitable via lzma.LZMADecompressor. Mitigation: upgrade to 3.14.5 or later.

Original description

The description as published by the source.

Use-after-free (UAF) was possible in the lzma.LZMADecompressor, bz2.BZ2Decompressor, and gzip.GzipFile when a memory allocation fails with a MemoryError and the decompression instance is re-used. This scenario can be triggered if the process is under memory pressure. The fix cleans up the dangling pointer in this specific error condition.

The vulnerability is only present if the program re-uses decompressor instances across multiple decompression calls even after a MemoryError is raised during decompression. Using the helper functions to one-shot decompress data such as lzma.decompress(), bz2.decompress(), gzip.decompress(), and zlib.decompress() are not affected as a new decompressor instance is used per call. If the decompressor instance is not re-used after an error condition, this usage is similarly not vulnerable.

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-2026-6100 has been found in python.
Attackers can target a specific entry point like lzma.LZMADecompressor over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 8.1/10.
What to do: upgrade python to 3.14.5 or later.
If unsure, ask your IT team or search "python CVE-2026-6100" on the vendor's site.

CVE-2026-6100 (python) — CWE-416 / CVSS v3 8.1
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: lzma.LZMADecompressor / bz2.BZ2Decompressor / gzip.GzipFile / MemoryError
Patched: 3.14.5 — 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

Use-after-free (CWE-416) exists in python. Attackers reach the vulnerable code path via lzma.LZMADecompressor without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of python. Attack surface: lzma.LZMADecompressor / bz2.BZ2Decompressor / gzip.GzipFile / MemoryError.

🔥 Severity

Severity: High (CVSS 8.1/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 3.14.5.

🛡️ 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 'python' . 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 'python' . | 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 python 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 python to 3.14.5

    ステージング環境で 3.14.5 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

Bitnami python
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.14.5"}]}]
Bitnami libpython
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.14.5"}]}]
Bitnami python-min
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"3.14.5"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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