CVE
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.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- Proof of concept public, per CISA
- Fix
- Fixed in 1.17.10
- Who is exposed
- Default setups
Do first: Check every install: default setups are affected.
- Last modified
- Whether it needs action now or is a reference record, by fixed rules, with why. Last checked is when cve.now last re-read it.What do these mean? →
- Reference
- Last checked
- FIRST's estimate of the chance attackers exploit it in the next 30 days, updated daily.What do these mean? →
- 0.75% · 55th percentile
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 50/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Default setups
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: poc
- Automatable: yes
- Technical impact: total
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.
Read the original 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.
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.
cve.now Index
- Exploitation15/40CISA rates a proof of concept as public
- Exposure25/25Default setups, CISA rates it automatable
- Reach?/20Unknown. No tracked technology or package matched
- Severity10/10CVSS 9.4, total technical impact per CISA
- No patch0/5No signal
What would change the score
- Would score about 75 if added to CISA KEV
- Would score about 70 if CISA's SSVC rates exploitation active
What to do
Check every install: default setups are affected.
Upgrade to a fixed version: 1.17.10.
Check your systems with an agent
Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.
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"}.Timeline
- CVE published
- First seen by cve.now
- Posted on X by cve.now1 day
- CISA SSVC assessment
Exploitation: poc · Automatable: yes · Technical impact: total
- Record last updated
Affected versions
- xyproto algernon
fixed in 1.17.10
Evidence 4
Vendor advisory · 1
Establishes: Affected and fixed versions.
- Advisory
CVE record · 2
Establishes: The identifier and description.
- Record
- Record
Other links · 1
- Repository
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-68548
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: cve.now feed data
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: github.com
Which versions are affected by CVE-2026-68548?
algernon: before 1.17.10.Source: cve.now feed data
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: github.com
How do I fix CVE-2026-68548?
Upgrade Algernon to version 1.17.10 or later, which contains the fix.Source: github.com