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🛡️ CVE-2026-34514 — aiohttp

🟢 CVSS 2.0 — Low ✅ No Known Exploit CWE-113 OSV
2.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

AIOHTTP has CRLF injection through multipart part content type header construction

Summary

An attacker who controls the content_type parameter in aiohttp could use this to inject extra headers or similar exploits.

Impact

If an application allows untrusted data to be used for the multipart content_type parameter when constructing a request, an attacker may be able to manipulate the request to send something other than what the developer intended.

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Patch: https://github.com/aio-libs/aiohttp/commit/9a6ada97e2c6cf1ce31727c6c9fcea17c21f6f06

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity low, availability none.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: None.
  • Integrity impact: Low — limited, and the attacker does not choose what is affected.
  • Availability impact: None.

Weakness class

CVE-2026-34514 is classified as CWE-113: HTTP Response Splitting. Unescaped input reaches an HTTP header, letting an attacker inject line breaks and forge additional headers or responses.

Affected software

CVE-2026-34514 is recorded against 1 package.

  • aiohttp (fixed in 3.13.4)

Timeline and source

Published on 1 April 2026 and last revised on 13 July 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from OSV.

References

github.com (Advisory)
github.com (Fix)
github.com (Fix)

Other advisories for this package

aiohttp has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-113: HTTP Response Splitting) in other software:

CVE-2026-34514 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity LOW
CVSS Score 2.0
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
CWE CWE-113
Public Exploit ✅ No
Source OSV
Published 2026-04-01
Updated 2026-08-20
Modified 2026-07-13

Affected Packages

Software From version Fixed in
aiohttp — 3.13.4

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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