CVE-2026-47265Network attack vector

Cookie disclosure via cross-origin redirect retention

Published Jun 2, 2026 · Updated Jun 2, 2026

Origin validation error in aio-libs aiohttp before 3.14.0 allows remote attackers to read per-request cookies via cross-origin redirects. The request redirect loop in aiohttp/client.py clears cookie headers when the redirect origin changes but retains the cookies parameter and reapplies those cookies to the new origin. Exposure requires an application to pass sensitive cookies per request and follow an attacker-controlled redirect; integrity and availability are unaffected.

CVSS severity7.5
High
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Origin validation error in aio-libs aiohttp before 3.14.0 allows remote attackers to read per-request cookies via cross-origin redirects. The request redirect loop in aiohttp/client.py clears cookie headers when the redirect origin changes but retains the cookies parameter and reapplies those cookies to the new origin. Exposure requires an application to pass sensitive cookies per request and follow an attacker-controlled redirect; integrity and availability are unaffected.

The record

CVE
CVE-2026-47265
Published
Jun 2, 2026
Updated
Jun 2, 2026
Vendor
aio-libs
Product
aiohttp
Classifications
CWE-346, T1539
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 2, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 2, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.14.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

aio-libs · aiohttpversion=< 3.14.0

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
6.6GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-346Origin Validation Error
T1539Steal Web Session Cookie

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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