# CVE-2016-5636: Integer overflow in n/a > Remote attackers can trigger a heap-based buffer overflow via negative data size values in the zipimport module, potentially leading to code execution or denial of service. - **Severity:** Critical 9.8 (`CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 2 Sep 2016 - **Updated:** 6 Aug 2024 - **Also known as:** AZL-109608, CLSA-2025-1757608338, CLSA-2025-1757608775, DEBIAN-CVE-2016-5636, GHSA-f5qq-9gj3-v9hw, PSF-2016-7, RHSA-2016:2586, UBUNTU-CVE-2016-5636 ## What is CVE-2016-5636? CVE-2016-5636 is a critical vulnerability in Python Python, published on 2 Sep 2016. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description Integer overflow in the get_data function in zipimport.c in CPython (aka Python) before 2.7.12, 3.x before 3.4.5, and 3.5.x before 3.5.2 allows remote attackers to have unspecified impact via a negative data size value, which triggers a heap-based buffer overflow. Weakness: CWE-190 (Integer Overflow or Wraparound) ## Which versions are affected by CVE-2016-5636? It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `python` | Red Hat:enterprise_linux:7::client | All versions | 0:2.7.5-48.el7 | | `python-debug` | Red Hat:enterprise_linux:7::client | All versions | 0:2.7.5-48.el7 | | `python-debuginfo` | Red Hat:enterprise_linux:7::client | All versions | 0:2.7.5-48.el7 | | `python-devel` | Red Hat:enterprise_linux:7::client | All versions | 0:2.7.5-48.el7 | | `python-libs` | Red Hat:enterprise_linux:7::client | All versions | 0:2.7.5-48.el7 | | `python-test` | Red Hat:enterprise_linux:7::client | All versions | 0:2.7.5-48.el7 | | `python-tools` | Red Hat:enterprise_linux:7::client | All versions | 0:2.7.5-48.el7 | | `tkinter` | Red Hat:enterprise_linux:7::client | All versions | 0:2.7.5-48.el7 | | `python` | Red Hat:enterprise_linux:7::computenode | All versions | 0:2.7.5-48.el7 | | `python-debug` | Red Hat:enterprise_linux:7::computenode | All versions | 0:2.7.5-48.el7 | | `python-debuginfo` | Red Hat:enterprise_linux:7::computenode | All versions | 0:2.7.5-48.el7 | | `python-devel` | Red Hat:enterprise_linux:7::computenode | All versions | 0:2.7.5-48.el7 | | `python-libs` | Red Hat:enterprise_linux:7::computenode | All versions | 0:2.7.5-48.el7 | | `python-test` | Red Hat:enterprise_linux:7::computenode | All versions | 0:2.7.5-48.el7 | | `python-tools` | Red Hat:enterprise_linux:7::computenode | All versions | 0:2.7.5-48.el7 | | `tkinter` | Red Hat:enterprise_linux:7::computenode | All versions | 0:2.7.5-48.el7 | | `python` | Red Hat:enterprise_linux:7::server | All versions | 0:2.7.5-48.el7 | | `python-debug` | Red Hat:enterprise_linux:7::server | All versions | 0:2.7.5-48.el7 | | `python-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 0:2.7.5-48.el7 | | `python-devel` | Red Hat:enterprise_linux:7::server | All versions | 0:2.7.5-48.el7 | | `python-libs` | Red Hat:enterprise_linux:7::server | All versions | 0:2.7.5-48.el7 | | `python-test` | Red Hat:enterprise_linux:7::server | All versions | 0:2.7.5-48.el7 | | `python-tools` | Red Hat:enterprise_linux:7::server | All versions | 0:2.7.5-48.el7 | | `tkinter` | Red Hat:enterprise_linux:7::server | All versions | 0:2.7.5-48.el7 | | `python` | Red Hat:enterprise_linux:7::workstation | All versions | 0:2.7.5-48.el7 | | `python-debug` | Red Hat:enterprise_linux:7::workstation | All versions | 0:2.7.5-48.el7 | | `python-debuginfo` | Red Hat:enterprise_linux:7::workstation | All versions | 0:2.7.5-48.el7 | | `python-devel` | Red Hat:enterprise_linux:7::workstation | All versions | 0:2.7.5-48.el7 | | `python-libs` | Red Hat:enterprise_linux:7::workstation | All versions | 0:2.7.5-48.el7 | | `python-test` | Red Hat:enterprise_linux:7::workstation | All versions | 0:2.7.5-48.el7 | | `python-tools` | Red Hat:enterprise_linux:7::workstation | All versions | 0:2.7.5-48.el7 | | `tkinter` | Red Hat:enterprise_linux:7::workstation | All versions | 0:2.7.5-48.el7 | Products: Python Python. ## How do I fix CVE-2016-5636? Upgrade to a fixed version. ## Is CVE-2016-5636 being exploited? There is no known exploitation of CVE-2016-5636 in the wild and no public exploit code. Public exploit code: - CVE-2016-5636 (github_poc): https://github.com/insuyun/CVE-2016-5636 ## Other vulnerabilities in Python Python - [CVE-2008-5031](https://insights.sbomify.com/CVE-2008-5031/): Integer overflow in n/a (critical 10.0) - [CVE-2014-4650](https://insights.sbomify.com/CVE-2014-4650/): Path traversal in n/a (critical 9.8) - [CVE-2007-4559](https://insights.sbomify.com/CVE-2007-4559/): Path traversal in n/a (critical 9.8) - [CVE-2017-17522](https://insights.sbomify.com/CVE-2017-17522/): Command injection in n/a (high 8.8) - [CVE-2026-15308](https://insights.sbomify.com/CVE-2026-15308/): Incremental HTMLParser feed() allows CPU-exhaustion DoS via repeated unterminated markup declarations (high 8.7) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2016-5636 and fix it if it is affected. What it is: CVE-2016-5636 is a critical vulnerability in Python Python, published on 2 Sep 2016. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2016-5636 in the wild and no public exploit code. Affected product: Python Python. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2016-5636/ (Markdown: https://insights.sbomify.com/CVE-2016-5636/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2016-5636 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2016-5636 - OSV: https://osv.dev/vulnerability/CVE-2016-5636 --- From sbomify Insights: https://insights.sbomify.com/CVE-2016-5636/ Summaries are generated and may contain mistakes; the official description above is the record.