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Fencer Vulns
medium 6.5

CVE-2026-26824 json

libxls through version 1.6.3 contains a use of uninitialized memory vulnerability in the OLE container parser.

published 2026-06-03 5 mo ago modified 2026-09-23 47 d ago also EUVD-2026-34178 , JLSEC-2026-1301

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 19%
public exploits
0
none known

Summary

libxls through version 1.6.3 contains a use of uninitialized memory vulnerability in the OLE container parser. Memory allocated for the Master Sector Allocation Table (MSAT) in read_MSAT() is not fully initialized before being consumed by ole2_validate_sector_chain(), which may result in application crashes or potential information disclosure when processing a crafted XLS file

Patch / fix

  • r-cran-readxl Debian 14 1.6.0-1

debian advisories DEBIAN-CVE-2026-26824

  • libxls openSUSE Leap 16.0 1.6.4-bp160.1.1
  • libxls openSUSE Tumbleweed 1.6.4-1.1

opensuse advisories openSUSE-SU-2026:22128-1openSUSE-SU-2026:12110-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-26824 updated cvss 5.6

libxls: libxls: Information disclosure via crafted XLS file processing

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
5 mo ago

Exploit prediction

0.27% chance of exploitation in the next 30 days, higher than 19% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/libxls/libxls/issues/155 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
OSV 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

Affected packages

ecosystem package affected fixed in
julia libxls_jll
all versions
 no fix listed

Classification

Weakness
  • CWE-457 Use of Uninitialized Variable

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.