# CVE-2013-1895: Improper Restriction of Excessive Authentication Attempts in py-bcrypt

> Attackers can bypass authentication in the py-bcrypt library by exploiting a race condition that overwrites password hashes during concurrent requests.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Jan 2020
- **Updated:** 6 Aug 2024
- **Also known as:** DEBIAN-CVE-2013-1895, GHSA-r838-q6jp-58xx, PYSEC-2020-249

## What is CVE-2013-1895?

CVE-2013-1895 is a high-severity vulnerability in Fedoraproject Fedora, published on 28 Jan 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

The py-bcrypt module before 0.3 for Python does not properly handle concurrent memory access, which allows attackers to bypass authentication via multiple authentication requests, which trigger the password hash to be overwritten.

Weakness: CWE-307 (Improper Restriction of Excessive Authentication Attempts)

## Which versions are affected by CVE-2013-1895?

3 open source packages ship an affected version, including py-bcrypt. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `py-bcrypt` | PyPI | All versions | 0.3 |
| `py-bcrypt` | PyPI | All versions | 0.3 |
| `py-bcrypt` | PyPI | All versions | 0.3 |

Products: Fedoraproject Fedora, Python Py-Bcrypt.

## How do I fix CVE-2013-1895?

Upgrade py-bcrypt to 0.3 or later.

## Is CVE-2013-1895 being exploited?

There is no known exploitation of CVE-2013-1895 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2013-1895 and fix it if it is affected.

What it is: CVE-2013-1895 is a high-severity vulnerability in Fedoraproject Fedora, published on 28 Jan 2020. 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-2013-1895 in the wild and no public exploit code.

Affected packages and fixed versions:
- py-bcrypt (PyPI): affected all versions; fixed in 0.3
- py-bcrypt (PyPI): affected all versions; fixed in 0.3
- py-bcrypt (PyPI): affected all versions; fixed in 0.3

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-2013-1895/ (Markdown: https://insights.sbomify.com/CVE-2013-1895/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2013-1895
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2013-1895
- OSV: https://osv.dev/vulnerability/CVE-2013-1895

---
From sbomify Insights: https://insights.sbomify.com/CVE-2013-1895/
Summaries are generated and may contain mistakes; the official description above is the record.