Security readout for executives and security teams
Plain-English summary
A crafted spreadsheet can trigger a memory corruption bug when LibreOffice Calc compiles an unusually long formula. Successful exploitation requires someone to open the file, but the CVSS impact is high for confidentiality, integrity, and availability.
Executive priority
Treat as high priority for fleets that handle external spreadsheets. Business urgency is highest where finance, operations, HR, or customer-service teams routinely open third-party spreadsheet files.
Technical view
CVE-2026-8357 is a heap buffer overflow in LibreOffice Calc formula compilation. A nesting-depth tracking array was allocated one element too small for worst-case formulas with many opening tokens, allowing a one-element out-of-bounds write. Sources list LibreOffice 26.2 as affected with unknown default status.
Likely exposure
Primary exposure is user workstations, VDI hosts, or document-processing systems where LibreOffice Calc 26.2 opens spreadsheets from email, downloads, portals, or third parties. The CVSS vector requires local file handling and user interaction, not direct network reachability.
Exploitation context
The supplied sources do not show CISA KEV listing or active exploitation. The plausible attack path is social delivery of a crafted spreadsheet that a user opens in Calc. No exploit code or weaponized procedure is needed to assess exposure.
Researcher notes
Evidence supports a heap overflow caused by an off-by-one allocation during formula compilation. The source bundle does not identify active exploitation, exploit maturity, or exact fixed LibreOffice version names, so validation should stay tied to vendor advisories and package metadata.
Mitigation direction
- Check LibreOffice and Red Hat advisories for fixed versions or packages.
- Prioritize updating systems with LibreOffice Calc 26.2 installed.
- Limit opening untrusted spreadsheets until patched.
- Use sandboxed document handling for externally sourced spreadsheets.
- Review Red Hat errata if using affected enterprise packages.
Validation and detection
- Inventory endpoints and servers for LibreOffice Calc 26.2.
- Confirm whether vendor-fixed LibreOffice or distribution packages are installed.
- Check email, web upload, and shared-drive workflows handling spreadsheets.
- Verify document-processing automation does not open untrusted spreadsheets unsandboxed.
- Track the CVE against vendor advisories and Red Hat VEX status.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-131: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-193: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-787: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-8357 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H1.85.9redhat-SADPCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:P——Document Fdn.Vulnerability scoring details
Base CVSS 4.0 score
5.4MediumVector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:P
Base CVSS 3.1 score
7.8HighVector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-06-15T18:01:23.824Z: Reported to Red Hat.
- 2026-06-15T16:23:37.518Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://www.libreoffice.org/about-us/security/advisories/cve-2026-8357CVE reference, Document Fdn.
- https://access.redhat.com/security/cve/CVE-2026-8357CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2488964CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-8357.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
- https://access.redhat.com/errata/RHSA-2026:35839CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/errata/RHSA-2026:36832CVE reference, redhat-SADP · vendor-advisory, x_refsource_REDHAT
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Incorrect Calculation of Buffer Size
Incorrect Calculation of Buffer Size represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Off-by-one Error
Off-by-one Error represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.