Out-of-bounds Read in AES-CFB-128 on X86-64 with AVX-512 Support
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- High · None · High
- Fix status
- Partial Red Hat: 1 fixed, 5 without a fix
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA and Red Hat.
Summary
Issue summary: Applications using AES-CFB128 encryption or decryption on systems with AVX-512 and VAES support can trigger an out-of-bounds read of up to 15 bytes when processing partial cipher blocks. Impact summary: This out-of-bounds read may trigger a crash which leads to Denial of Service for an application if the input buffer ends at a memory page boundary and the following page is unmapped. There is no information disclosure as the over-read bytes are not written to output. The vulnerable code path is only reached when processing partial blocks (when a previous call left an incomplete block and the current call provides fewer bytes than needed to complete it). Additionally, the input buffer must be positioned at a page boundary with the following page unmapped. CFB mode is not used in TLS/DTLS protocols, which use CBC, GCM, CCM, or ChaCha20-Poly1305 instead. For these reasons the issue was assessed as Low severity according to our Security Policy. Only x86-64 systems with AVX-512 and VAES instruction support are affected. Other architectures and systems without VAES support use different code paths that are not affected. OpenSSL FIPS module in 3.6 version is affected by this issue.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA OpenSSL (OpenSSL) Fixed in 3.6.2
Red Hat 1 advisory
- RHSA-2026:7261 Released 2026-04-09 · Red Hat rating ImportantRed Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images openssl-3.5.6-0.1.hum1@aarch64, openssl-3.5.6-0.1.hum1@src, openssl-3.5.6-0.1.hum1@x86_64 +10
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Advisory ·
OpenSSL — openssl-library.org/news/secadv/20260407.txt
7 records Highest priority Priority MEDIUM 6 MEDIUM, 1 LOW
Other records, highest priority first
- TI-2026-24345 Heap Buffer Overflow in Hexadecimal ConversionPriority MEDIUM 42
- TI-2026-24346 Incorrect Failure Handling in RSA KEM RSASVE EncapsulationPriority MEDIUM 41
- TI-2026-22663 NULL Pointer Dereference When Processing a Delta CRLPriority MEDIUM 41
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 7 | Affected | No fix yet |
| Red Hat Enterprise Linux 8 | Affected | No fix yet |
| Red Hat Enterprise Linux 9 | Affected | No fix yet |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet |
| Red Hat Hardened Images | Fixed | RHSA-2026:7261 |
Not affected: 6 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat JBoss Core Services
Timeline
- 2026-10-02 Threatist record created from CVE-2026-28386
- 2026-10-03 Alias added: GHSA-q457-vx59-3fqg
References
Patch 1
Advisory 1
More Openssl vulnerabilities
- TI-2022-01915 The c_rehash script allows command injection CVSS 3.1CRITICAL 9.8
- TI-2021-02645 SM2 Decryption Buffer Overflow CVSS 3.1CRITICAL 9.8
- TI-2009-03392 The TLS protocol, and the SSL protocol 3.0 and possibly earlier, as used in Microsoft… CVSS 3.1CRITICAL 9.8
- TI-2022-01176 The c_rehash script allows command injection CVSS 3.1CRITICAL 9.8
- TI-2014-00154 The (1) TLS and (2) DTLS implementations in OpenSSL 1.0.1 before 1.0.1g do not properly… KEVCVSS 3.1HIGH 7.5
- TI-2025-14107 Stack buffer overflow in CMS (Auth)EnvelopedData parsing CVSS 3.1HIGH 8.8
Sources
- CVE-2026-28386 · CVE Program
- CVE-2026-28386 · NVD
- FIRST EPSS
- GHSA-q457-vx59-3fqg · GitHub Advisory Database · CC BY 4.0
- CVE-2026-28386 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences