CVE-2026-48503 Information disclosure in libiec61850
Remote attackers can read stale buffer data via MMS file service flaws in libIEC61850 when the file service is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-48503?
CVE-2026-48503 is a high-severity vulnerability in mz-automation libiec61850, published on 16 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
libIEC61850 is an open-source implementation of IEC 61850 client and server protocols including MMS, GOOSE, Sampled Values, and R-Session. Prior to 1.6.2, the MMS file service in src/mms/iso_mms/server/mms_file_service.c accepts an out-of-range initialPosition in fileOpen and stores it in the file-read state. The fileRead path then subtracts the larger read position from the file size using unsigned arithmetic and fails to limit the response to the actual FileSystem_readFile return value. The oversized response can include stale bytes from the reused connection buffer after the requested file contents, disclosing prior response data and protocol fragments to an unauthenticated remote client when the file service is enabled. This issue is fixed in version 1.6.2.
Which versions are affected by CVE-2026-48503?
How do I fix CVE-2026-48503?
No fix has been published for CVE-2026-48503 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-48503 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-48503 exists.
Sources
Also known as GHSA-4c8m-jr3r-h8j2.