GHSA-cq5v-8q36-5273 CVE-2026-69244 PYSEC-2026-3545
AIOHTTP: Out-of-bounds heap read in C HTTP response parser error path (malformed chunked response)
- Severity
- 0.0 / 10
- High · CVSS 4.0
- Exploit chance (EPSS)
- 0.53%
- Chance of exploitation in the next 30 days. Higher than 44.71% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Fix
3.14.3- Upgrade aiohttp to this version or later
Description
Summary
An out-of-bounds heap read could occur in the C response parser while building an error message for a malformed response.
Impact
An attacker controlled server, or possibly an accidental response could trigger a DoS in the client.
Workaround
If unable to upgrade, the Python parser is unaffected and can be used with AIOHTTP_NO_EXTENSIONS=1.
Patch: https://github.com/aio-libs/aiohttp/commit/49f65d54150397892f7bcc4aae887767d51c322d
Affected versions
PyPI
| Package | Vulnerable | Fixed in |
|---|---|---|
| aiohttp | < 3.14.3 |
3.14.3 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
aiohttp PyPI → 3.14.3
- pip
pip install --upgrade "aiohttp>=3.14.3"- poetry
poetry add "aiohttp>=3.14.3"- uv
uv add "aiohttp>=3.14.3"
Severity breakdown
CVSS 4.0 0.0
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- None
- Privileges required
- None
- User interaction
- Passive
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- None
- Availability (vulnerable system)
- High
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
Weakness
CWE-125: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How to prevent it
- Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.
- Architecture and Design: Use a language that provides appropriate memory abstractions.
CWE-400: Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource.
How to prevent it
- Architecture and Design: Design throttling mechanisms into the system architecture. The best protection is to limit the amount of resources that an unauthorized user can cause to be expended. A strong authentication and access control model will help prevent such attacks from occurring in the first place. The login application should be protected against DoS attacks as much as possible. Limiting the database access, perhaps by caching result sets, can help minimize the resources expended. To further limit the potential for a DoS attack, consider tracking the rate of requests received from users and blocking requests that exceed a defined rate threshold.
- Architecture and Design: Mitigation of resource exhaustion attacks requires that the target system either: recognizes the attack and denies that user further access for a given amount of time, or uniformly throttles all requests in order to make it more difficult to consume resources more quickly than they can again be freed. The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question. The second solution is simply difficult to effectively institute -- and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
- Architecture and Design: Ensure that protocols have specific limits of scale placed on them.
- Implementation: Ensure that all failures in resource allocation place the system into a safe posture.
CWE-416: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
How to prevent it
- Architecture and Design: Choose a language that provides automatic memory management.
- Implementation: When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-pqxq-w44r-73xw AIOHTTP: Pure-Python parser request smuggling | Medium | Also affects aiohttp |
| GHSA-gx76-c99x-2c96 AIOHTTP: Cookie from subdomain can remove Host-Only Scope from existing cookies | Low | Also affects aiohttp |
| GHSA-f9xw-jh8m-3mwq AIOHTTP: Absolute-form request targets can spoof Request.scheme | Medium | Also affects aiohttp |
| GHSA-9xw5-w5jj-pvcg AIOHTTP: File descriptor exhaustion in multipart requests | High | Also affects aiohttp |
| GHSA-6cjc-53gc-5rqm AIOHTTP: Connector pool exhaustion via Max-Age overflow | Medium | Also affects aiohttp |
| GHSA-5wr8-gcqf-gqf3 aiohttp server lacks an initial request/header timeout | High | Also affects aiohttp |
| GHSA-494j-54xm-rwp3 AIOHTTP: Secure attribute not enforced for shared cookie | Medium | Also affects aiohttp |
| GHSA-2g87-pp6c-29x5 aiohttp: Multiple instances of excessive or unbounded memory/CPU use | High | Also affects aiohttp |
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