CVE-2025-69224VulnerabilityPublished 5 Jan 2026

CVE-2025-69224: aio-libs aiohttp · HTTP Request/Response Smuggling

Affects aio-libs aiohttpSource CVE Database V5

Not known to be exploited · CVSS 6.3 Medium : upgrade to 3.13.3 when convenient.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 4.0 base score

6.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 3.13.3

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: Present
Privileges Required: None
User Interaction: None
Vulnerable system confidentiality: Low
Vulnerable system integrity: Low
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: Present: The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: a race condition must be won to successfully exploit the vulnerability (the successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker, or the attack may need to be launched multiple times against a single target before being successful); the attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 5 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade aio-libs aiohttp to 3.13.3.

Affected software

Product	Affected	Fixed in
aio-libsaiohttp	Affected <3.13.3	Fixed in 3.13.3
PyPIaiohttp`pkg:pypi/aiohttp`Other threats	Affected <3.13.3	Fixed in 3.13.3

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

1. Upgrade aiohttp to version 3.13.3 or later immediately to apply the official fix. 2. Audit Python environments to ensure that the C extensions for aiohttp are enabled and that the AIOHTTP_NO_EXTENSIONS environment variable is not set, as the vulnerability only manifests when the pure Python parser is used. 3. Review and harden proxy and firewall configurations to detect and block anomalous HTTP requests, particularly those containing non-ASCII characters or unusual header sequences. 4. Implement logging and monitoring for HTTP request anomalies that may indicate request smuggling attempts. 5. Conduct penetration testing or use specialized tools to simulate request smuggling attacks against internal applications using aiohttp to validate defenses. 6. Educate development and operations teams about the risks of disabling C extensions and the importance of keeping dependencies up to date. 7. Where possible, deploy web application firewalls (WAFs) with signatures or heuristics capable of detecting request smuggling patterns. 8. Isolate critical services behind additional layers of security to limit the impact of potential request smuggling exploitation.

Description

CVE-2025-69224 is a medium severity HTTP request smuggling vulnerability in aiohttp versions prior to 3.13.3. It affects the Python HTTP parser when non-ASCII characters are present and the pure Python implementation is used (i.e. , without C extensions or when AIOHTTP_NO_EXTENSIONS is enabled). This flaw allows attackers to bypass certain firewalls or proxy protections by crafting malicious HTTP requests that are inconsistently interpreted by intermediaries and the server. Exploitation does not require authentication or user interaction but does require network access to the vulnerable server. No known exploits are currently reported in the wild. The vulnerability impacts confidentiality and integrity by enabling request smuggling attacks that can lead to unauthorized request execution or data leakage.

Impact

For European organizations, the impact of CVE-2025-69224 can be significant depending on their use of aiohttp in server-side applications, especially those exposed to the internet or internal networks with proxy/firewall protections. Successful exploitation could allow attackers to bypass security controls, leading to unauthorized access, data leakage, or manipulation of HTTP requests and responses. This undermines confidentiality and integrity of communications and may facilitate further attacks such as session hijacking, web cache poisoning, or cross-site scripting. Organizations in sectors with strict data protection requirements (e.g., finance, healthcare, government) could face compliance risks and reputational damage if exploited. The medium severity score reflects that while the attack is feasible without authentication or user interaction, the requirement for specific parser configurations (pure Python) limits the scope somewhat. Nonetheless, the widespread use of Python and aiohttp in web services across Europe means many organizations could be affected if they have not updated or audited their aiohttp deployments. The lack of known exploits in the wild suggests a window of opportunity for proactive mitigation before active exploitation occurs.

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') (opens in a new tab)
Base weaknessOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
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.
Implementation
Use a web server that employs a strict HTTP parsing procedure, such as Apache.
Implementation
Use only SSL communication.
Implementation
Terminate the client session after each request.
OWASP Cheat Sheets
REST Assessment (opens in a new tab)
REST Security (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
Secure Design Principles (opens in a new tab)
OWASP ASVS 4.0.3
V13.2.5 (opens in a new tab)
Attack patterns
HTTP Response Smuggling (opens in a new tab)
HTTP Request Smuggling (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 13 Jan 2026, 01:01 UTC

WeaknessesCWE-444

Technical details

References

Community reviews

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