CVE-2026-26825: A use-of-uninitialized memory vulnerability exists in libxls 1.6.3 when parsing malformed XLS files.
Noroxi assessment
Priority: Monitor (action score 21/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.24% (FIRST EPSS).
- 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.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: r-cran-readxl (Debian:14) 1.6.0-1; libxls (openSUSE:Leap 16.0) 1.6.4-bp160.1.1; libxls (openSUSE:Tumbleweed) 1.6.4-1.1.
Low priority for now. Upgrade to r-cran-readxl (Debian:14) 1.6.0-1; libxls (openSUSE:Leap 16.0) 1.6.4-bp160.1.1; libxls (openSUSE:Tumbleweed) 1.6.4-1.1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
A use-of-uninitialized memory vulnerability exists in libxls 1.6.3 when parsing malformed XLS files. The issue is reachable via xls_parseWorkBook() and is triggered by uninitialized heap memory originating from the OLE layer (ole2_read). The flaw is detectable with MemorySanitizer (MSAN) and can lead to undefined behavior, incorrect parsing logic, or potential information disclosure.
- Published
- Jun 3, 2026
- Updated
- Sep 23, 2026
- EPSS
- 0.2% · 15th percentile
- CWE
- CWE-908
Report tools
Action score
21
Monitor
Low priority for now.
- CVSS
- 21 / 40 · 5.3 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.2%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
Running WordPress? Scan your site free with WP Lens
Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| libxls project | libxls | cpe:2.3:a:libxls_project:libxls |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- libxls project libxls1.6.3
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | r-cran-readxl | from 0 | — |
| Debian:14 | r-cran-readxl | before 1.6.0-1 | 1.6.0-1 |
| openSUSE:Leap 16.0 | libxls | before 1.6.4-bp160.1.1 | 1.6.4-bp160.1.1 |
| openSUSE:Tumbleweed | libxls | before 1.6.4-1.1 | 1.6.4-1.1 |
Same product
libxls project: all recordsOther highest-scoring records for the same primary product.
- CVE-2017-2910An exploitable Out-of-bounds Write vulnerability exists in the xls_addCell function of libxls 2.0.36Monitor
- CVE-2017-12109An exploitable integer overflow vulnerability exists in the xls_preparseWorkSheet function of libxls 1.4 when handling a MULRK record.36Monitor
- CVE-2017-12108An exploitable integer overflow vulnerability exists in the xls_preparseWorkSheet function of libxls 1.4 when handling a MULBLANK record.36Monitor
Published before and after this one in the same product
- ← EarlierCVE-2023-38855Aug 15, 2023 · Buffer Overflow vulnerability in libxlsv.1.6.2 allows a remote attacker to execute arbitrary code and cause a denial of service via a crafte26Monitor
- ← EarlierCVE-2023-38856Aug 15, 2023 · Buffer Overflow vulnerability in libxlsv.1.6.2 allows a remote attacker to execute arbitrary code and cause a denial of service via a crafte26Monitor
- ← EarlierCVE-2026-26824Jun 3, 2026 · libxls through version 1.6.3 contains a use of uninitialized memory vulnerability in the OLE container parser.26Monitor
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 |
|---|---|---|
| debian:r-cran-readxl | 1.6.0-1 · Debian:14 | Package registry (OSV) |
| opensuse:libxls | 1.6.4-1.1 · openSUSE:Tumbleweed | 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.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
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-908 · Use of Uninitialized ResourceCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (1 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.