GHSA-3c37-wwvx-h642 · 深刻度： high · エコシステム： pip — cbor2 has a Denial of Service via Uncontrolled Recursion in cbor2.loads
cbor2 provides encoding and decoding for the Concise Binary Object Representation (CBOR) serialization format. Versions prior to 5.9.0 are vulnerable to a Denial of Service (DoS) attack caused by uncontrolled recursion when decoding deeply nested CBOR structures. This vulnerability affects both the pure Python implementation and the C extension `_cbor2`. The C extension relies on Python's internal recursion limits `Py_EnterRecursiveCall` rather than a data-driven depth limit, meaning it still raises `RecursionError` and crashes the worker process when the limit is hit. While the library handles moderate nesting levels, it lacks a hard depth limit. An attacker can supply a crafted CBOR payload containing approximately 100,000 nested arrays `0x81`. When `cbor2.loads()` attempts to parse this, it hits the Python interpreter's maximum recursion depth or exhausts the stack, causing the process to crash with a `RecursionError`. Because the library does not enforce its own limits, it allows an external attacker to exhaust the host application's stack resource. In many web application servers (e.g., Gunicorn, Uvicorn) or task queues (Celery), an unhandled `RecursionError` terminates the worker process immediately. By sending a stream of these small (<100KB) malicious packets, an attacker can repeatedly crash worker processes, resulting in a complete Denial of Service for the application. Version 5.9.0 patches the issue.
総合評価: CVE-2026-26209 は公開エクスプロイトあり（57/100）。CVSS 深刻度は高。悪用される可能性が高い（EPSS 0.42%、33 パーセンタイル） 根拠: 公開エクスプロイトが 1 件参照されています（Exploit-DB）。 推奨対応: 公開エクスプロイトが確認されています。影響範囲の確認、緩和策の適用、パッチ適用を優先してください。
リスクは変動します。再評価に基づき、本ページの表示内容を更新しています。
| EDB-ID | ソース | 種別 | 公開 | リンク |
|---|---|---|---|---|
| — | nvd_ref | exploit_tag | Exploit-DB ↗ |
EPSS は日次で悪用されやすさの相対度合いを推定します。パーセンタイルは採点済み CVE の中での相対位置（高いほど相対的に深刻）を示します。
| # | 日付 | 旧 EPSS スコア | 新 EPSS スコア | Δ（新 − 旧） |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.06% | 0.42% | +0.36% |
| 2 | 2026-03-29 | 0.04% | 0.06% | +0.01% |
| 3 | 2026-03-24 | — | 0.04% | — |
EPSS の全履歴 （全 3 件）
この CVE の CVSS 指標。
| ベーススコア | バージョン | 深刻度 | ベクトル | 悪用しやすさ | 影響 | スコアの出典 |
|---|---|---|---|---|---|---|
| 7.5 | 3.0 | HIGH |
|
3.9 | 3.6 | [email protected] |
GHSA-3c37-wwvx-h642 · 深刻度： high · エコシステム： pip — cbor2 has a Denial of Service via Uncontrolled Recursion in cbor2.loads
| vendor | priority | summary | link |
|---|---|---|---|
alpine
|
— | CVE-2026-26209: 1 source package rows (py3-cbor2); 3 state rows across 2 repos (3.23-community, edge-community); fixed 0, open 3. | https://security.alpinelinux.org/vuln/CVE-2026-26209 |
debian
|
not yet assigned | CVE-2026-26209 not yet assigned priority: Debian including 1 source packages (cbor2), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. | https://security-tracker.debian.org/tracker/CVE-2026-26209 |
redhat
|
medium | — | https://access.redhat.com/security/cve/CVE-2026-26209 |
suse
|
high | CVE-2026-26209 severity important: SUSE including 3 source package names (python311-cbor2-5.9.0-1.1, python313-cbor2-5.6.5-160000.4.1, python313-cbor2-5.9.0-1.1), 4 product×package rows across 3 product lines (SUSE Linux Enterprise Server 16.0, openSUSE Leap 16.0, openSUSE Tumbleweed): Fixed 3, First Fixed 1. | https://www.suse.com/security/cve/CVE-2026-26209/ |
ubuntu
|
medium | CVE-2026-26209 medium priority: Ubuntu including 1 source packages (cbor2), 4 status rows across 4 suites (jammy, noble, questing, upstream): needs-triage 4. | https://ubuntu.com/security/CVE-2026-26209 |
| URL | タグ |
|---|---|
| https://github.com/agronholm/cbor2/commit/e61a5f365ba610d5907a0ae1bc72769bba34294b | Patch |
| https://github.com/agronholm/cbor2/pull/275 | Issue Tracking Patch |
| https://github.com/agronholm/cbor2/releases/tag/5.9.0 | Product Release Notes |
| https://github.com/agronholm/cbor2/security/advisories/GHSA-3c37-wwvx-h642 | Exploit Vendor Advisory |