CVE-2026-48111 — 7-zip / 7-zip
Out-of-bounds Read7-Zip is a file archiver with a high compression ratio. Versions 9.21 through 26.00 contain an off-by-one out-of-bounds read vulnerability in the ParseDepedencyExpression function of the UEFI firmware image parser(CPP/7zip/Archive/UefiHandler.cpp). The function validates an attacker-controlled opcode byte using > instead of >= against the element count of the 10-entry kExpressionCommands static array, allowing an opcode value of 10 to read one pointer slot (8 bytes on x64) past the end of the array in .rodata. The out-of-bounds value is then dereferenced as a const char * and passed through strlen and memcpy into the archive's Characts property, which may cause either a denial of service (access violation when the adjacent bytes do not form a valid readable pointer) or a minor information disclosure of an adjacent .rdata string literal into archive metadata. The vulnerability is reached automatically during IInArchive::Open() via the call path OpenFv/OpenCapsule → ParseVolume → ParseSections when processing a SECTION_DXE_DEPEX (0x13) or SECTION_PEI_DEPEX (0x1B) section whose first body byte is 0x0A, and the UEFI handler is enabled by default in stock 7z.dll with signature-based detection for both UEFIc and UEFIf formats. The outcome (crash vs. silent leak) is deterministic per build but linker-layout dependent, with no write primitive and no disclosure of heap data, secrets, or ASLR base addresses. Version 26.01 fixes the issue.
| Software | From | Fixed in |
|---|---|---|
| 7-zip / 7-zip | 9.21 | 26.01 |
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Frequently Asked Questions
A security vulnerability is a weakness in software, hardware, or configuration that can be exploited to compromise confidentiality, integrity, or availability. Many vulnerabilities are tracked as CVEs (Common Vulnerabilities and Exposures), which provide a standardized identifier so teams can coordinate patching, mitigation, and risk assessment across tools and vendors.
CVSS (Common Vulnerability Scoring System) estimates technical severity, but it doesn't automatically equal business risk. Prioritize using context like internet exposure, affected asset criticality, known exploitation (proof-of-concept or in-the-wild), and whether compensating controls exist. A "Medium" CVSS on an exposed, production system can be more urgent than a "Critical" on an isolated, non-production host.
A vulnerability is the underlying weakness. An exploit is the method or code used to take advantage of it. A zero-day is a vulnerability that is unknown to the vendor or has no publicly available fix when attackers begin using it. In practice, risk increases sharply when exploitation becomes reliable or widespread.
Recurring findings usually come from incomplete Asset Discovery, inconsistent patch management, inherited images, and configuration drift. In modern environments, you also need to watch the software supply chain: dependencies, containers, build pipelines, and third-party services can reintroduce the same weakness even after you patch a single host. Unknown or unmanaged assets (often called Shadow IT) are a common reason the same issues resurface.
Use a simple, repeatable triage model: focus first on externally exposed assets, high-value systems (identity, VPN, email, production), vulnerabilities with known exploits, and issues that enable remote code execution or privilege escalation. Then enforce patch SLAs and track progress using consistent metrics so remediation is steady, not reactive.
SynScan combines attack surface monitoring and continuous security auditing to keep your inventory current, flag high-impact vulnerabilities early, and help you turn raw findings into a practical remediation plan.