PatchSiren

PatchSiren cyber security CVE debrief

CVE-2025-0725 Siemens CVE debrief

CVE-2025-0725 is a high-severity memory-corruption issue in the libcurl/zlib handling path described by Siemens and CISA. In affected Siemens industrial products, automatic gzip decompression of HTTP content-encoded responses can trigger an attacker-controlled integer overflow and then a buffer overflow. Siemens and CISA identify update guidance for affected products, with remediation to V3.3 or later.

Vendor
Siemens
Product
RUGGEDCOM RST2428P (6GK6242-6PA00)
CVSS
HIGH 7.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-01-28
Original CVE updated
2026-02-25
Advisory published
2026-01-28
Advisory updated
2026-02-25

Who should care

Operators and maintainers of Siemens industrial networking and OT devices listed in the advisory, especially environments running SINEC OS firmware on RUGGEDCOM RST2428P and related SCALANCE product lines. This matters most where devices may process untrusted HTTP traffic or rely on the affected libcurl/zlib combination.

Technical summary

The issue is described as occurring when libcurl is configured for automatic gzip decompression via CURLOPT_ACCEPT_ENCODING and uses zlib 1.2.0.3 or older. Under those conditions, an attacker-controlled integer overflow can cause libcurl to write beyond a buffer, creating a buffer overflow condition. The CVSS v3.1 vector supplied is AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L, which indicates network reachability, low complexity, no privileges, and no user interaction.

Defensive priority

High

Recommended defensive actions

  • Apply the Siemens remediation and update affected devices to V3.3 or later.
  • Inventory Siemens products against the advisory’s affected product list and verify whether SINEC OS firmware is in use.
  • Reduce exposure of affected OT devices by segmenting networks and limiting unnecessary HTTP access to managed interfaces.
  • Follow CISA industrial control system defense-in-depth and recommended practices while patching is being planned or deployed.

Evidence notes

Source evidence comes from CISA CSAF advisory ICSA-26-043-06 and Siemens ProductCERT advisory SSA-089022. The supplied advisory text states that automatic gzip decompression of content-encoded HTTP responses with CURLOPT_ACCEPT_ENCODING, using zlib 1.2.0.3 or older, can lead to an attacker-controlled integer overflow and buffer overflow. The remediation field recommends updating to V3.3 or later for the affected product sets. CISA published the advisory on 2026-01-28 and republished/updated it on 2026-02-12, 2026-02-24, and 2026-02-25.

Official resources

CVE-2025-0725 was publicly published on 2026-01-28 and later updated by CISA on 2026-02-12, 2026-02-24, and 2026-02-25 based on Siemens ProductCERT advisory SSA-089022. The underlying issue is tied to Siemens advisory coverage for multiple;