Vulnerability in aiohttp (CVE-2026-59881)
Summary
Vulnerability in aiohttp (CVE-2026-59881). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 3.14.2 or later.
Original description
The description as published by the source.
Summary
The client accepts and decompresses frames with the RSV1 bit set even when the permessage-deflate extension was not negotiated.
Impact
A client may unexpectedly decompress WebSocket frames when explicitly opted out. This could lead to additional CPU/memory consumption, but is unlikely to be a significant issue unless a zip bomb vulnerability or similar is also present.
Patch: https://github.com/aio-libs/aiohttp/commit/47fb6ae354d4fa22048f4dbe7dbf82b625f0a2f6
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-2026-59881 has been found in aiohttp.
Risk of unauthorized operations or information disclosure.
What to do: upgrade aiohttp to 3.14.2 or later.
If unsure, ask your IT team or search "aiohttp CVE-2026-59881" on the vendor's site.
CVE-2026-59881 (aiohttp) — CWE-20
Patched: 3.14.2 — 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.
A vulnerability (CWE-20) exists in aiohttp.
Check the vendor advisory for the affected versions of aiohttp.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 3.14.2.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'aiohttp' . 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
-
1Identify exposure identify
grep -r 'aiohttp' . | 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
aiohttpを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade aiohttp to 3.14.2ステージング環境で 3.14.2 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。
-
3Post-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
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-59881 python-aiohttp
- Ubuntu UBUNTU-CVE-2026-59881 python-aiohttp
References
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- package pypi.org
- web github.com
- web github.com
- web github.com
- web github.com