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Medium, CVSS 5.3amended

ezBookkeeping: Source-IP allowlist (MCP & API token) is bypassable via a spoofed X-Forwarded-For header

CVE-2026-86041GHSA-wchh-mrv2-5h4q

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/mayswind/ezbookkeeping 1.6.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
5.3 · CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N · score source
EPSS
  • CVE-2026-86041: 0.22% estimated exploitation activity in the next 30 days; percentile 12.76 (FIRST EPSS, 2026-11-10). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary A remote attacker from any IP address defeats the operator-configured source-IP allowlist (`mcp_allowed_remote_ips` / `api_token_allowed_remote_ips`) by sending a single `X-Forwarded-For: ` header. The router is created with `gin.New()` and never calls `SetTrustedProxies`, so gin trusts every proxy by default and `c.ClientIP()` returns the attacker-supplied header verbatim. The same forged value is also written to `Transaction.CreatedIp` and the access log, so the attacker's real IP never appears in any record.

Details `cmd/webserver.go:104` builds the router with `gin.New()`. A grep of `cmd/` and `pkg/` confirms `SetTrustedProxies` is never called, leaving gin's default trusted-proxy range of `0.0.0.0/0` and `::/0`. `WebContext` (`pkg/core/context_web.go:39`) embeds `*gin.Context` and does not override `ClientIP()`. Both allowlist middlewares match the operator allowlist against this attacker-controlled value: ```go // pkg/middlewares/mcp_server_ip_limit.go:19 if…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from osv record GHSA-wchh-mrv2-5h4q

  2. Revision 1 · created ·

    Published from ghsa record GHSA-wchh-mrv2-5h4q

Agent brief

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# Patch Next advisory brief: CVE-2026-86041

Advisory: ezBookkeeping: Source-IP allowlist (MCP & API token) is bypassable via a spoofed `X-Forwarded-For` header
IDs: CVE-2026-86041, GHSA-wchh-mrv2-5h4q
Record: https://patchnext.com/advisories/cve-2026-86041 (revision 2, source checked 10 Nov 2026, 06:45 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/mayswind/ezbookkeeping 1.6.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/mayswind/ezbookkeeping: affected >= 0.10.0, < 1.6.0; fixed in 1.6.0

## Suggested inspection (read-only)
- Go github.com/mayswind/ezbookkeeping: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/mayswind/ezbookkeeping.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-wchh-mrv2-5h4q (GitHub-reviewed advisory GHSA-wchh-mrv2-5h4q lists affected ranges: Go github.com/mayswind/ezbookkeeping >=0.10.0 <1.6.0)
- Verified: https://osv.dev/vulnerability/GHSA-wchh-mrv2-5h4q (OSV record GHSA-wchh-mrv2-5h4q lists affected ranges: Go github.com/mayswind/ezbookkeeping >=0.10.0 <1.6.0 (fixed))

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