chmextract.c in the chmextract sample program, as distributed with libmspack before 0.8alpha, does not protect against absolute/relative pat
chmextract.c in the chmextract sample program, as distributed with libmspack before 0.8alpha, does not protect against absolute/relative pathnames in CHM files, leading to Directory Traversal. NOTE: the vendor disputes that this is a libmspack vulnerability, because chmextract.c was only intended as a source-code example, not a supported application
Noroxi analysis
No Noroxi analysis for this record yet
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We use this product, ask for help- Published
- Oct 22, 2018
- Updated
- Jun 16, 2026
- EPSS
- 3.3% · 88th percentile
- CWE
- CWE-22
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Report tools
Action score
22
Monitor
Low priority for now.
- CVSS
- 21 / 40 · 5.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 3.3%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| kyzer | libmspack | cpe:2.3:a:kyzer:libmspack |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- kyzer libmspack0.3
- kyzer libmspack0.4
- kyzer libmspack0.5
- kyzer libmspack0.6
- kyzer libmspack0.7
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.10 | libmspack | before 0.8_alpha-r0 | 0.8_alpha-r0 |
| Debian:12 | libmspack | before 0.8-1 | 0.8-1 |
| openSUSE:Leap 15.3 | libmspack | before 0.6-3.14.1 | 0.6-3.14.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP3 | libmspack | before 0.6-3.14.1 | 0.6-3.14.1 |
| SUSE:Linux Enterprise Software Development Kit 12 SP5 | libmspack | before 0.4-15.13.1 | 0.4-15.13.1 |
Same product
kyzer: all recordsOther highest-scoring records for the same primary product.
- CVE-2019-1010305libmspack 0.9.1alpha is affected by: Buffer Overflow.22Monitor
- CVE-2018-18585chmd_read_headers in mspack/chmd.c in libmspack before 0.8alpha accepts a filename that has '\0' as its first or second character (such as t18Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| alpine:libmspack | 0.8_alpha-r0 · Alpine:v3.10 | Package registry (OSV) |
| debian:libmspack | 0.8-1 · Debian:12 | Package registry (OSV) |
| opensuse:libmspack | 0.6-3.14.1 · openSUSE:Leap 15.3 | Package registry (OSV) |
| suse:libmspack | 0.6-3.14.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP3 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- low · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- Low
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')CVSS vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
nvd-primary
Root cause
A user-supplied file name is joined with the allowed directory, but the result is never checked to confirm it is still inside that directory.
The bug in code
The whole CWE-22 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
const file = path.join(ROOT, req.query.name);res.sendFile(file);Fixed
const file = path.resolve(ROOT, req.query.name);if (!file.startsWith(ROOT + path.sep)) { return res.sendStatus(400);}res.sendFile(file);Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Path TraversalCAPEC-126likelihood: High · Very High
- Using Slashes and URL Encoding Combined to Bypass Validation LogicCAPEC-64likelihood: High · High
- Manipulating Web Input to File System CallsCAPEC-76likelihood: High · Very High
- Using Escaped Slashes in Alternate EncodingCAPEC-78likelihood: High · High
- Using Slashes in Alternate EncodingCAPEC-79likelihood: High · High
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- bugs.debian.org/911639
- security.gentoo.org/glsa/201903-20
- www.openwall.com/lists/oss-security/2018/10/22/1
Vendor advisories and official records. Exploit/PoC links are deliberately left out.