CVE-2026-59881
published 2026-07-30CVE-2026-59881: AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the WebSocket client accepts and decompresses frames with the…
PriorityP340medium6.9CVSS 4.0
AVNACLATNPRNUINVCNVINVALSCNSINSANEXCRXIRXARXMAVXMACXMATXMPRXMUIXMVCXMVIXMVAXMSCXMSIXMSAXSXAUXRXVXREXUX
EPSS
0.52%
43.6th percentile
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the WebSocket client accepts and decompresses frames with the RSV1 bit set even when the permessage-deflate extension was not negotiated, allowing a malicious server to cause unexpected CPU and memory consumption. This issue is fixed in version 3.14.2.
Affected
131 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| aio-libs | aiohttp | < 3.14.2 | 3.14.2 |
| aiohttp | aiohttp | >= 0 < 3.14.2 | 3.14.2 |
| ansible-automation-platform-24 | controller-rhel8 | — | — |
| ansible-automation-platform-24 | de-minimal-rhel8 | — | — |
| ansible-automation-platform-24 | de-minimal-rhel9 | — | — |
| ansible-automation-platform-24 | de-supported-rhel8 | — | — |
| ansible-automation-platform-24 | de-supported-rhel9 | — | — |
| ansible-automation-platform-24 | ee-supported-rhel8 | — | — |
| ansible-automation-platform-24 | ee-supported-rhel9 | — | — |
| ansible-automation-platform-24 | hub-rhel8 | — | — |
| ansible-automation-platform-24 | lightspeed-rhel8 | — | — |
| ansible-automation-platform-25 | controller-rhel8 | — | — |
| ansible-automation-platform-25 | de-minimal-rhel8 | — | — |
| ansible-automation-platform-25 | de-minimal-rhel9 | — | — |
| ansible-automation-platform-25 | ee-supported-rhel8 | — | — |
| ansible-automation-platform-25 | ee-supported-rhel9 | — | — |
| ansible-automation-platform-25 | hub-rhel8 | — | — |
| ansible-automation-platform-25 | lightspeed-chatbot-rhel8 | — | — |
| ansible-automation-platform-25 | lightspeed-rhel8 | — | — |
| ansible-automation-platform-26 | ansible-dev-tools-rhel9 | — | — |
| ansible-automation-platform-26 | controller-rhel9 | — | — |
| ansible-automation-platform-26 | de-minimal-rhel9 | — | — |
| ansible-automation-platform-26 | de-supported-rhel9 | — | — |
| ansible-automation-platform-26 | ee-minimal-rhel9 | — | — |
| ansible-automation-platform-26 | ee-supported-rhel9 | — | — |
CVSS provenance
nvdv4.06.9MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vendor_redhat6.9MEDIUM
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GHSA
AIOHTTP: WebSocket client accepts compressed frames without negotiated permessage-deflate
ghsa·2026-08-03
CVE-2026-59881 [MEDIUM] CWE-20 AIOHTTP: WebSocket client accepts compressed frames without negotiated permessage-deflate
AIOHTTP: WebSocket client accepts compressed frames without negotiated permessage-deflate
### 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
VulDB
aio-libs aiohttp up to 3.14.1 WebSocket Client input validation
vuldb·2026-07-30·CVSS 6.9
CVE-2026-59881 [MEDIUM] aio-libs aiohttp up to 3.14.1 WebSocket Client input validation
A vulnerability, which was classified as problematic, was found in aio-libs aiohttp up to 3.14.1. Affected by this vulnerability is an unknown functionality of the component WebSocket Client. Such manipulation leads to improper input validation.
This vulnerability is referenced as CVE-2026-59881. It is possible to launch the attack remotely. No exploit is available.
You should upgrade the affected component.
Red Hat
aiohttp: AIOHTTP: Denial of Service via unnegotiated WebSocket compression
vendor_redhat·2026-07-30·CVSS 6.9
CVE-2026-59881 [MEDIUM] CWE-409 aiohttp: AIOHTTP: Denial of Service via unnegotiated WebSocket compression
aiohttp: AIOHTTP: Denial of Service via unnegotiated WebSocket compression
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the WebSocket client accepts and decompresses frames with the RSV1 bit set even when the permessage-deflate extension was not negotiated, allowing a malicious server to cause unexpected CPU and memory consumption. This issue is fixed in version 3.14.2.
A flaw was found in AIOHTTP. The WebSocket client in AIOHTTP processes compressed data frames even when the compression mechanism, known as permessage-deflate, has not been properly negotiated. A malicious server can exploit this by sending specially crafted compressed frames. This can lead to unexpected and excessive consumption of the system's central processing unit (
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-59881 python-aiohttp: AIOHTTP: Denial of Service via unnegotiated WebSocket compression [fedora-all]
bugzilla·2026-07-31·CVSS 6.9
CVE-2026-59881 [MEDIUM] CVE-2026-59881 python-aiohttp: AIOHTTP: Denial of Service via unnegotiated WebSocket compression [fedora-all]
CVE-2026-59881 python-aiohttp: AIOHTTP: Denial of Service via unnegotiated WebSocket compression [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the WebSocket client accepts and decompresses frames with the RSV1 bit set even when the permessage-deflate extension was not negotiated, allowing a malicious server to cause unexpected CPU and memory consumption. This issue is fixed in version 3.14.2.
Discussion:
In Rawhide, this should be fixed by updating to 3.14.2 or later.
In F44/F43, this can’t be fixed th
Bugzilla
CVE-2026-59881 python-aiohttp: AIOHTTP: Denial of Service via unnegotiated WebSocket compression [epel-all]
bugzilla·2026-07-31·CVSS 6.9
CVE-2026-59881 [MEDIUM] CVE-2026-59881 python-aiohttp: AIOHTTP: Denial of Service via unnegotiated WebSocket compression [epel-all]
CVE-2026-59881 python-aiohttp: AIOHTTP: Denial of Service via unnegotiated WebSocket compression [epel-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to 3.14.2, the WebSocket client accepts and decompresses frames with the RSV1 bit set even when the permessage-deflate extension was not negotiated, allowing a malicious server to cause unexpected CPU and memory consumption. This issue is fixed in version 3.14.2.
Discussion:
In EPEL10, this can’t be fixed by updating because several intervening “minor” releases contained docu
2026-07-30
Published