BlackTreeCVE Intelligence
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Full vulnerability report · 2023
CVE-2023-37276High confidence

aiohttp vulnerable to HTTP request smuggling

aio-libs · aiohttp

Official source article: GitHub GHSA-45C4-8WX5-QW6W ↗. Check the applicable product and release in the original source.

5.3MediumCVSS 3.1
Recommended action
Patch only the product branches with a verified fix

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityMediumOperational priority:High, raised one band.upgradedsince 18 Oct 2024

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 1.34% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs aio-libs aiohttp and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Distribution package intelligence

Release-specific package status

Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

4 package states
Package result overrides the generic status

BlackTree has verified remediation for at least one product or source, but the relevant distribution still reports no fixed package for 1 affected package state shown here. Treat those rows as affected with no fix until that distribution publishes a fixed version.

Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Debian trixietrixie · sourcepython-aiohttpVendor fix publishedDebian records a fixed source-package version for this release.3.8.5-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian bookwormbookworm · sourcepython-aiohttpAffected, no fix publishedDebian currently tracks this release as open.Not published in this feedDebian Security Tracker ↗Source updated 5 Oct 2026
Debian forkyforky · sourcepython-aiohttpVendor fix publishedDebian records a fixed source-package version for this release.3.8.5-1Debian Security Tracker ↗Source updated 5 Oct 2026
Debian sidsid · sourcepython-aiohttpVendor fix publishedDebian records a fixed source-package version for this release.3.8.5-1Debian Security Tracker ↗Source updated 5 Oct 2026
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2023-0003

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

Medium technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance. Verified remediation exists for at least one product or source, but 1 structured product or package state remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. aiohttp v3.8.4 and earlier are bundled with llhttp v6.0.6. Vulnerable code is used by aiohttp for its HTTP request parser when available which is the default case when installing from a wheel. This vulnerability only affects users of aiohttp as an HTTP server (ie `aiohttp.Application`), you are not affected by this vulnerability if you are using aiohttp as an HTTP client library (ie `aiohttp.ClientSession`). Sending a crafted HTTP request will cause the server to misinterpret one of the HTTP header values leading to HTTP request smuggling. This issue has been addressed in version 3.8.5. Users are advised to upgrade. Users unable to upgrade can reinstall aiohttp using `AIOHTTP_NO_EXTENSIONS=1` as an environment variable to disable the llhttp HTTP request parser implementation. The pure Python implementation isn't vulnerable.

What

aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. aiohttp v3.8.4 and earlier are bundled with llhttp v6.0.6. Vulnerable code is used by aiohttp for its HTTP request parser when available which is the default case when installing from a wheel. This vulnerability only affects users of aiohttp as an HTTP server (ie `aiohttp.Application`), you are not affected by this vulnerability if you are using aiohttp as an HTTP client library (ie `aiohttp.ClientSession`). Sending a crafted HTTP request will cause the server to misinterpret one of the HTTP header values leading to HTTP request smuggling. This issue has been addressed in version 3.8.5. Users are advised to upgrade. Users unable to upgrade can reinstall aiohttp using `AIOHTTP_NO_EXTENSIONS=1` as an environment variable to disable the llhttp HTTP request parser implementation. The pure Python implementation isn't vulnerable.

Why

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.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

aiohttp is an asynchronous HTTP client/server framework for asyncio and Python. aiohttp v3.8.4 and earlier are bundled with llhttp v6.0.6. Vulnerable code is used by aiohttp for its HTTP request parser when available which is the default case when installing from a wheel. This vulnerability only affects users of aiohttp as an HTTP server (ie `aiohttp.Application`), you are not affected by this vulnerability if you are using aiohttp as an HTTP client library (ie `aiohttp.ClientSession`). Sending a crafted HTTP request will cause the server to misinterpret one of the HTTP header values leading to HTTP request smuggling. This issue has been addressed in version 3.8.5. Users are advised to upgrade. Users unable to upgrade can reinstall aiohttp using `AIOHTTP_NO_EXTENSIONS=1` as an environment variable to disable the llhttp HTTP request parser implementation. The pure Python implementation isn't vulnerable.

Why

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.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-444 ↗

CWE-444: Inconsistent 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.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.ILowIntegrity impact: A successful attack can cause a limited loss.ANoneAvailability impact: No direct loss is represented by this metric.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedCWE-444Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

BSI · German · WID-SEC-2024-0949Red Hat Satellite: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Red Hat Satellite ausnutzen, um Sicherheitsmaßnahmen zu umgehen, einen Denial-of-Service-Zustand herbeizuführen, vertrauliche Informationen offenzulegen, Dateien zu manipulieren, HTTP-Request-Smuggling-Angriffe durchzuführen oder Phishing- und Cross-Site-Scripting (XSS)-Angriffe auszuführen.

Official advisory ↗
Cyber Security Agency of Singapore · English · CSA-SB-20230726Security Bulletin 26 Jul 2023

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 26 Jul 2023, published on 26 July 2023. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0535Multiples vulnérabilités dans les produits Splunk

ord?id=CVE-2022-40897 Référence CVE CVE-2022-40898 https://www.cve.org/CVERecord?id=CVE-2022-40898 Référence CVE CVE-2022-40899 https://www.cve.org/CVERecord?id=CVE-2022-40899 Référence CVE CVE-2023-2976 https://www.cve.org/CVERecord?id=CVE-2023-2976 Référence CVE CVE-2023-32681 https://www.cve.org/CVERecord?id=CVE-2023-32681 Référence CVE CVE-2023-34453 https://www.cve.org/CVERecord?id=CVE-2023-34453 Référence CVE CVE-2023-34454 https://www.cve.org/CVERecord?id=CVE-2023-34454 Référence CVE CVE-2023-34455 https://www.cve.org/CVERecord?id=CVE-2023-34455 Référence CVE CVE-2023-35116 https://www.cve.org/CVERecord?id=CVE-2023-35116 Référence CVE CVE-2023-37276 https://www.cve.org/CVERecord?id=CVE-2023-37276 Référence CVE CVE-2023-37920 https://www.cve.org/CVERecord?id=CVE-2023-37920 Référence CVE CVE-2023-39410 https://www.cve.org/CVERecord?id=CVE-2023-39410 Référence CVE CVE-2023-43642 https://www.cve.org/CVERecord?id=CVE-2023-43642 Référence CVE CVE-2023-43804 https://www.cve.org/CVERecord?id=CVE-2023-43804 Référence CVE CVE-2023-45803 https://www.cve.org/CVERecord?id=CVE-2023-45803 Référence CVE CVE-2023-47627 https://www.cve.org/CVERecord?id=CVE-2023-47627 Référence CVE CVE-2023-5752 https://www.cve.org/CVERecord?id=CVE-2023-5752 Référence CVE CVE-2024-3651 https://www.cve.org/CVERecord?id=CVE

Official advisory ↗
CERT-FR · French · CERTFR-2024-AVI-0145Multiples vulnérabilités dans les produits IBM

ecord?id=CVE-2023-33850 Référence CVE CVE-2023-34053 https://www.cve.org/CVERecord?id=CVE-2023-34053 Référence CVE CVE-2023-34054 https://www.cve.org/CVERecord?id=CVE-2023-34054 Référence CVE CVE-2023-34055 https://www.cve.org/CVERecord?id=CVE-2023-34055 Référence CVE CVE-2023-34062 https://www.cve.org/CVERecord?id=CVE-2023-34062 Référence CVE CVE-2023-3446 https://www.cve.org/CVERecord?id=CVE-2023-3446 Référence CVE CVE-2023-34462 https://www.cve.org/CVERecord?id=CVE-2023-34462 Référence CVE CVE-2023-3611 https://www.cve.org/CVERecord?id=CVE-2023-3611 Référence CVE CVE-2023-36665 https://www.cve.org/CVERecord?id=CVE-2023-36665 Référence CVE CVE-2023-37276 https://www.cve.org/CVERecord?id=CVE-2023-37276 Référence CVE CVE-2023-3776 https://www.cve.org/CVERecord?id=CVE-2023-3776 Référence CVE CVE-2023-37920 https://www.cve.org/CVERecord?id=CVE-2023-37920 Référence CVE CVE-2023-38003 https://www.cve.org/CVERecord?id=CVE-2023-38003 Référence CVE CVE-2023-38325 https://www.cve.org/CVERecord?id=CVE-2023-38325 Référence CVE CVE-2023-38545 https://www.cve.org/CVERecord?id=CVE-2023-38545 Référence CVE CVE-2023-38546 https://www.cve.org/CVERecord?id=CVE-2023-38546 Référence CVE CVE-2023-38552 https://www.cve.org/CVERecord?id=CVE-2023-38552 Référence CVE CVE-2023-38719 https://www.cve.org/CVERecord?id=CV

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2023-023324aiohttp project の aiohttp における HTTP リクエストスマグリングに関する脆弱性

aiohttp project の aiohttp には、HTTP リクエストスマグリングに関する脆弱性が存在します。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix availability varies by product
Affected
aiohttp: < 3.8.5
Fixed
3.8.5.
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 19 Jul 2023 · Last source change 18 Oct 2024, 17:14 UTC · CWE-444 · Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

CVE recordCVE.org · 5.1
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2023-0003
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD modified after enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2023-37276 · cve.blacktree.nl