CVE-2026-62958: Input Validation Flaw (CVSS 7.9)

Description

libriscv is a RISC-V sandbox and emulator. Prior to 1.18, a crafted ELF binary can cause out-of-bounds reads in the host emulator. `Memory<W>::binary_loader` checks `PT_LOAD` program-header bounds, but `Memory<W>::serialize_execute_segment` trusts section-header `sh_offset` and `sh_size` when locating `.text` without verifying the file range against `m_binary.size()`; `Memory<W>::lookup()` has a similar section-table problem. Malformed `.text` or `.symtab` offsets can therefore bypass the program-header checks and point outside the binary buffer, crashing rvlinux. With suitable memory layout or integer overflow, out-of-buffer host heap memory may instead be mapped into the guest by `create_execute_segment()`, potentially exposing host memory. The reported reproducer demonstrates a host SIGSEGV, while memory disclosure through grooming is described as possible rather than demonstrated. This issue is fixed in version 1.18.

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CVSS v3.1 Score

7.9

HIGH

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:H

Weakness Type (CWE)

CWE-20 Improper Input Validation

CWE-125 Out-of-bounds Read

References

Other References

https://github.com/libriscv/libriscv/commit/61ef9ca82c8876dd80b33780893ba512af780e93 https://github.com/libriscv/libriscv/commit/7bd1c189f9f9d54368cde096b07b194ad680f9fa https://github.com/libriscv/libriscv/releases/tag/v1.18 https://github.com/libriscv/libriscv/security/advisories/GHSA-gm4g-6c78-gr3w

Frequently Asked Questions

What is CVE-2026-62958? +

libriscv is a RISC-V sandbox and emulator. Prior to 1.18, a crafted ELF binary can cause out-of-bounds reads in the host emulator. `Memory<W>::binary_loader` checks `PT_LOAD` program-header bounds, but `Memory<W>::serialize_execute_segment` trusts section-header `sh_offset` and `sh_size` when locating `.text` without verifying the file range against `m_binary.size()`; `Memory<W>::lookup()` has a similar section-table problem. Malformed `.text` or `.symtab` offsets can therefore bypass the program-header checks and point outside the binary buffer, crashing rvlinux. With suitable memory layout or integer overflow, out-of-buffer host heap memory may instead be mapped into the guest by `create_execute_segment()`, potentially exposing host memory. The reported reproducer demonstrates a host SIGSEGV, while memory disclosure through grooming is described as possible rather than demonstrated. This issue is fixed in version 1.18. It has a CVSS v3.1 base score of 7.9 (HIGH).

How severe is CVE-2026-62958? +

CVE-2026-62958 has a CVSS v3.1 score of 7.9 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

How do I check if I'm vulnerable to CVE-2026-62958? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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