Analyst readout for executives and security teams
Plain-English summary
This is a high-severity Chrome PDF handling flaw. A user opening a malicious PDF in an outdated browser could expose the device to serious compromise. The bundle does not show active exploitation, but browser flaws with low attack complexity can move quickly.
Executive priority
Treat this as a near-term browser patching priority. It is not confirmed exploited in the provided sources, but the impact is high and the exposure path is common: opening PDFs in Chrome.
Technical view
CVE-2026-9958 is a CWE-416 use-after-free in Chrome PDFium before 148.0.7778.216. The CVSS 3.1 score is 8.8, with network attack vector, low complexity, no privileges required, and user interaction required. Impact is rated high for confidentiality, integrity, and availability.
Likely exposure
Exposure is likely where desktop Chrome is below 148.0.7778.216 and users can open PDFs from email, web pages, or downloads in Chrome. The bundle does not identify other affected Google products or downstream Chromium-based browsers.
Exploitation context
The source bundle describes potential heap corruption through a crafted PDF file. It does not provide evidence of active exploitation, and KEV status is false. User interaction is required, so phishing or malicious document delivery is the likely risk context.
Researcher notes
The public bundle identifies PDFium use-after-free and crafted-PDF heap corruption, but not root-cause details or proof-of-concept material. Chromium issue details may be restricted. Avoid assuming exploitability beyond the CVSS and vendor description.
Mitigation direction
- Update Google Chrome to 148.0.7778.216 or later where available.
- Check Google Chrome release guidance for platform-specific update details.
- Prioritize managed browser update enforcement across desktops and laptops.
- Limit PDF handling in outdated Chrome until patched.
- Monitor vendor advisories for revised affected-version guidance.
Validation and detection
- Inventory Chrome versions across managed endpoints.
- Confirm installed Chrome versions are at least 148.0.7778.216.
- Review browser management reports for update failures.
- Check whether Chrome is the default PDF viewer on endpoints.
- Track exceptions for systems unable to update promptly.
Public sources used
Based on public source material and reviewed before publication.
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-416: 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-2026-9958 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
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/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
1 official scoreWe 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:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H 2.8 5.9 CISA-ADP Vulnerability scoring details
Base CVSS 3.1 score
8.8 HighVector: CVSS:3.1/AV:N/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 reserved CVE Program
The CVE ID was reserved by the assigning CNA.
- CVE published CVE Program
The CVE record was published.
- CVE updated CVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 source CVE List V5
- https://chromereleases.googleblog.com/2026/05/stable-channel-update-for-desktop_0877304591.html CVE reference, Chrome
- https://issues.chromium.org/issues/504555886 CVE reference, Chrome
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.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.