CVE-2026-34525: aio-libs aiohttp Improper Input Validation
CVSS: 6.3v4.0MediumAnalyzed
AliasesGHSA-c427-h43c-vf67PYSEC-2026-2103UBUNTU-CVE-2026-34525DEBIAN-CVE-2026-34525CGA-283r-w6rp-rmcjCGA-29cw-rgjf-43prCGA-29v2-2g69-2g5gCGA-5xc7-wqfh-j64xCGA-66hc-37jg-8j88CGA-73xj-f2m4-8xmwCGA-8fc8-3fgw-6wpqCGA-942x-hm35-c4ggCGA-9mg8-49r7-pv7fCGA-f4pj-3xx5-pm63CGA-gv2g-26wv-8rhhCGA-h7gm-fx2v-46r4CGA-hfj6-rp2x-992qCGA-pq79-px4f-gg7mCGA-q45h-pwc7-7422CGA-rc24-m3wv-c33cCGA-v7qj-8gh7-jmp9CGA-22p9-xrvm-c2v3CGA-38cx-88pf-5chjCGA-4492-72c5-j9wqCGA-54m9-4738-74x5CGA-6c9v-j7wf-f487CGA-6g9f-35jw-fh9pCGA-6mrw-w48x-hw6vCGA-6v35-w955-5pc6CGA-7h27-682f-vvm9CGA-875r-422v-wxphCGA-88fj-wvrg-chm5CGA-8mpx-q9jc-4fcqCGA-8rfv-6g89-q9f8CGA-8w6q-w2rr-7jgxCGA-8wwq-j8c9-3mpmCGA-c87w-j24p-9v6rCGA-cf98-hmcr-9635CGA-f34p-4mmh-cfq9CGA-f9fw-w637-46xvCGA-fvg4-crgj-v2cqCGA-gg73-xjpf-vp7jCGA-ghf7-vc8m-4vj3CGA-gw4q-f3cp-34jjCGA-gxmv-j25c-wcmhCGA-h9f4-3xcj-wvfgCGA-hqfv-cqp9-92r5CGA-jq7m-x8vh-f49pCGA-jqgm-x45q-8xc2CGA-mjfg-w97r-j57cCGA-p9rg-wg6q-4cwgCGA-pw93-9993-v7cwCGA-q67q-3hrw-q9wrCGA-q7x8-fprr-9x3pCGA-q9rq-p77h-jqwcCGA-qc74-33mj-r2j2CGA-qfp5-fg2r-7r7gCGA-qmq3-2xrf-c5wcCGA-r49x-69qw-9v4xCGA-rq2g-q7cp-747gCGA-rx8m-r5ff-g5wrCGA-vh3j-8gc8-rw6hCGA-wqx6-xv72-9p4vCGA-x936-h584-w26m
Published 01-04-2026Last modified 23-06-2026
Vulnerability summary
CVE-2026-34525 is a medium (CVSS 6.3) Improper Input Validation vulnerability in aio-libs aiohttp. EPSS estimates a 0.39% chance of exploitation in the next 30 days, higher than 31.9% of scored vulnerabilities.
CVSS score
6.3/10
010
Medium · v4.0 (CVE.org)EPSS score
0.39%
0%100%
Low · +0.11 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 4 · Related 5Timeline
- 01-04-2026PublishedVulnerability first disclosed.
- 23-06-2026Last modifiedVulnerability information updated.
Description
AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, multiple Host headers were allowed in aiohttp. This issue has been patched in version 3.13.4.
CVSS metrics
9 scores · 7 sources · 2 versionsMedium 6.3Preferred score · CVE.org (CNA)
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:NSourcesAll 5 agree
- OSV · UbuntuEcosystem advisory · calculated6.3MediumCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N
- OSV · WolfiEcosystem advisory · calculated6.3MediumCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N
- OSV · ChainguardEcosystem advisory · calculated6.3MediumCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N
- NVDNIST6.3MediumCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/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
Medium 5.3Preferred score · OSV · Pypi (Ecosystem advisory) · calculated from vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:NSourcesAll 4 agree
- OSV · UbuntuEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- OSV · DebianEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
- NVDNIST5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
EPSS trend
Probability
0.39%
Chance of exploitation in the next 30 days
Percentile
32%
Versus all other CVEs
30-day change
+0.11 pp
From 0.29% on 20-09-2026
20-09-202620-10-2026
EPSS score0.39%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-20Improper Input ValidationThe product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
- CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')The product acts as an intermediary HTTP agent (such as a proxy or firewall) in the data flow between two entities such as a client and server, but it does not interpret malformed HTTP requests or responses in ways that are consistent with how the messages will be processed by those entities that are at the ultimate destination.
Affected systems
Chainguard26 products
- airflow-2< 2.11.2-r5
- airflow-3< 3.2.1-r0 | < 3.1.8-r11
- airflow-core-2< 2.11.2-r3
- authentik-2025.12< 2025.12.4-r3
- authentik-2026.2< 2026.2.1-r3
Wolfi7 products
- airflow-3< 3.2.1-r0 | < 3.1.8-r11
- checkov< 3.2.517-r0
- dask-kubernetes< 2026.3.0-r3
- kserve-storage-controller< 0.17.0-r2
- kubeflow-pipelines-visualization-server< 2.16.0-r4
Aio-libs1 product
- aiohttp< 3.13.4
Aiohttp1 product
- aiohttp< 3.13.4
Debian1 product
- python-aiohttpAll versions (No fix recorded) | < 3.13.5-1
PyPI1 product
- aiohttp< 3.13.4
Ubuntu1 product
- python-aiohttpAll versions (No fix recorded)
7 vendors · 38 products
References
10 links- github.com/aio-libs/aiohttp/security/advisories/GHSA-c427-h43c-vf67X Refsource CONFIRMWEBFIXREPORTAdvisoryPatchVendor Advisory
- github.com/aio-libs/aiohttp/commit/53e2e6fc58b89c6185be7820bd2c9f40216b3000X Refsource MISCWEBFIXREPORTPatch
- github.com/aio-libs/aiohttp/commit/e00ca3cca92c465c7913c4beb763a72da9ed8349X Refsource MISCWEBFIXREPORTPatch
- github.com/aio-libs/aiohttpPACKAGE
