Improper Link Resolution Before File Access ('Link Following') in hMailServer
- Exploited
- No known exploitation
- Fix
- Fixed in 6.3.8
- Who is exposed
- Specific setups only
Do first: Upgrade to a fixed version: 6.3.8.
- Published
- 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
- 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? →
- 13/100 · 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? →
- Specific setups only
- 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
Summary
A local user with a low-privilege login can run code as the mail server's service account or as an administrator in Progressive Robot hMailServer. They do this by pointing the program folder path through a junction, symbolic link, or mount point during Windows installation, so the programs get installed and started from a location that user controls.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
Improper link resolution in the Windows installer of Progressive Robot hMailServer 6.0.0 through 6.3.7 allows a local authenticated user to run code as the mail server's service account or as an administrator when the path to the program folder passes through a junction, a symbolic link or a mount point that the user controls or that every user may change, such as a junction made at the root of a drive, which takes the root's permissions, or through a folder that every user may rename. Setup installed the programs through any such link without first checking who controls it, or whether a folder above the program folder may be renamed, and the service is registered to run the programs by that path, so the programs are installed where a link another account controls leads, or that account can later make the path lead to a folder it controls; the service, which runs as LocalSystem or as its virtual account, and the programs administrators run from Bin are then started from there. 6.3.7's fix for CVE-2026-107571 does not cover this: its hardening of the program folder, Bin and ControlPanel does not change a folder reached through a link that the administrators do not alone control, and setup does not refuse such a path: it installs through the link and at most reports afterwards that the folders could not be hardened. The default installation under Program Files is not affected.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure5/25Specific setups only
- Reach?/20Unknown. No tracked technology or package matched
- Severity7.8/10CVSS 7.8
- No patch0/5No signal
What would change the score
- Would score about 63 if added to CISA KEV
- Would score about 58 if CISA's SSVC rates exploitation active
- Would score about 23 if CISA's SSVC rates it automatable
What to do
Upgrade to a fixed version: 6.3.8.
Workaround: Install hMailServer under Program Files, or at a path with no link on it below folders that only administrators may change, until upgraded.
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-2026-126612 (Improper Link Resolution Before File Access ('Link Following') in hMailServer), 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-2026-126612 (entry last updated 2026-11-11):
Affected:
- Progressive Robot Ltd hMailServer: from 6.0.0, through 6.3.7
Fixed versions: 6.3.8.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: local access, low-privilege login, no user action.
Workaround: Install hMailServer under Program Files, or at a path with no link on it below folders that only administrators may change, until upgraded. (source: https://www.cve.org/CVERecord?id=CVE-2026-126612)
CISA KEV: CVE-2026-126612 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126612 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://gitlab.com/hmailserver/hmailserver/-/work_items/78
- https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.8
- https://www.cve.org/CVERecord?id=CVE-2026-107571
- https://www.cve.org/CVERecord?id=CVE-2026-126612
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-2026-126612
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-2026-126612.Timeline
- CVE published
- First seen by cve.now
Affected versions
- Progressive Robot Ltd hMailServer
From 6.0.0 · through 6.3.7
Evidence 5
CVE record · 3
Establishes: The identifier and description.
- Record
- Record
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-126612
Is CVE-2026-126612 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. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-126612?
hMailServer: from 6.0.0 through 6.3.7.Source: cve.now feed data
How do I fix CVE-2026-126612?
Upgrade hMailServer to version 6.3.8, which is the fixed release. Until you upgrade, the workaround is to install hMailServer under Program Files, or at a path with no link on it below folders that only administrators may change.Source: cve.org