Google OSS Agent Mesh: Three Critical Vulnerabilities Disclosed Together
Key findings • Three critical vulnerabilities disclosed in Google OSS Agent Mesh (SAM) between October 18-19, 2026. • CVE-2026-103091 and CVE-2026-102503 involve authorization and authenticat…
Key findings
- Three critical vulnerabilities disclosed in Google OSS Agent Mesh (SAM) between October 18-19, 2026.
- CVE-2026-103091 and CVE-2026-102503 involve authorization and authentication bypass in SAM's proxy and ingress server.
- Affected SAM versions include 0.1.0-alpha.1 through 0.1.0-alpha.2.
- CVE-2026-98816 addresses a BPF jump offset overflow in the Linux kernel.
On October 18-19, 2026, a batch of three critical vulnerabilities was disclosed in Google's OSS Agent Mesh (SAM), a service mesh designed for managing services across various environments. The vulnerabilities, disclosed within an 11-hour window, collectively pose significant security risks, including unauthorized access and potential bypass of security controls.
Two of the vulnerabilities, CVE-2026-103091 and CVE-2026-102503, directly impact the SAM proxy and its ingress server. CVE-2026-103091, found in the MCP proxy and OIDC registration flow, suffers from Missing Authorization (CWE-862) and Initialization of a Resource with an Insecure Default (CWE-1188). This could allow unauthorized actors to gain access to sensitive operations. Similarly, CVE-2026-102503, located in the /libp2p-http ingress server, involves Missing Authentication for Critical Function (CWE-306) and Missing Authorization (CWE-862). This flaw permits an unauthenticated remote libp2p peer to bypass critical security capabilities. Both these vulnerabilities affect SAM versions from 0.1.0-alpha.1 through 0.1.0-alpha.2.
The third vulnerability, CVE-2026-98816, resides in the Linux kernel, which underpins many systems where SAM might operate. This issue is a fix for an overflow of a jump offset in constant blinding within the BPF (Berkeley Packet Filter) JIT (Just-In-Time) compiler. Specifically, the bpf_jit_blind_insn() function, when rewriting jump instructions, could encounter an overflow with the s16 jump offset, potentially leading to unexpected behavior or security implications in how BPF programs are executed. This vulnerability was disclosed on October 18, 2026.
The combined impact of these vulnerabilities suggests a need for vigilant security practices for users of Google OSS Agent Mesh. The critical nature of CVE-2026-103091 and CVE-2026-102503 highlights potential avenues for attackers to compromise the integrity and confidentiality of services managed by SAM. The Linux kernel vulnerability, while distinct, underscores the importance of maintaining a secure underlying operating system.
Google's OSS Agent Mesh (SAM) versions 0.1.0-alpha.1 through 0.1.0-alpha.2 are affected by the critical SAM-specific vulnerabilities. The Linux kernel vulnerability, CVE-2026-98816, has been addressed with a fix for the jump offset overflow in bpf_jit_blind_insn(). Users are advised to consult Google's security advisories for specific patching information and recommended mitigation strategies for SAM, and to ensure their Linux kernels are up-to-date to address the BPF-related issue.
This coordinated disclosure of critical vulnerabilities in Google's OSS Agent Mesh and a related Linux kernel issue serves as a reminder of the complex security landscape in distributed systems. Users should prioritize updating their SAM instances and underlying infrastructure to the latest patched versions to protect against potential exploitation.