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NVD / CVE Program· CNA openssl

CVE-2026-28386: Out-of-bounds Read in AES-CFB-128 on X86-64 with AVX-512 Support

Noroxi assessment

Priority: Monitor (action score 30/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.51% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: OpenSSL OpenSSL 3.6.2.

Low priority for now. Upgrade to OpenSSL OpenSSL 3.6.2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
Apr 7, 2026
Updated
Jul 24, 2026
EPSS
0.5% · 44th percentile

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-28386

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
opensslopenssl

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Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • openssl openssl3.6.0 and later · before 3.6.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (openssl). Independent of NVD's CPE analysis and usually ahead of it.

  • OpenSSL OpenSSL

    • 3.6.0 and later · before 3.6.2affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:14opensslbefore 3.6.2-13.6.2-1
Red Hat:hummingbird:1opensslbefore 0:3.5.6-0.1.hum10:3.5.6-0.1.hum1
Red Hat:hummingbird:1openssl-config-fipsbefore 0:3.5.6-0.1.hum10:3.5.6-0.1.hum1
Red Hat:hummingbird:1openssl-develbefore 0:3.5.6-0.1.hum10:3.5.6-0.1.hum1
Red Hat:hummingbird:1openssl-devel-enginebefore 0:3.5.6-0.1.hum10:3.5.6-0.1.hum1
Red Hat:hummingbird:1openssl-libsbefore 0:3.5.6-0.1.hum10:3.5.6-0.1.hum1
Red Hat:hummingbird:1openssl-perlbefore 0:3.5.6-0.1.hum10:3.5.6-0.1.hum1

Same product

openssl: all records

Other highest-scoring records for the same primary product.

  • CVE-2014-0160The (1) TLS and (2) DTLS implementations in OpenSSL 1.0.1 before 1.0.1g do not properly handle Heartbeat Extension packets, which allows remKEV
    90Now
  • CVE-2021-3711SM2 Decryption Buffer Overflow
    65This week
  • CVE-2003-0545Double free vulnerability in OpenSSL 0.9.7 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code
    65This week

Published before and after this one in the same product

  • ← EarlierCVE-2025-15467Jan 27, 2026 · Stack buffer overflow in CMS (Auth)EnvelopedData parsing
    57Plan
  • ← EarlierCVE-2026-2673Mar 13, 2026 · OpenSSL TLS 1.3 server may choose unexpected key agreement group
    26Monitor
  • Later →CVE-2026-28387Apr 7, 2026 · Potential Use-after-free in DANE Client Code
    32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
OpenSSL OpenSSL3.6.2Vendor (CNA)
debian:openssl3.6.2-1 · Debian:14Package registry (OSV)
red hat:openssl0:3.5.6-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-config-fips0:3.5.6-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-devel0:3.5.6-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-devel-engine0:3.5.6-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-libs0:3.5.6-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-perl0:3.5.6-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-84782175 days apartDTLS Retransmits Handshake Messages From a Stale Buffer Offset
    32Monitor
  • CVE-2026-3418063 days apartHeap Buffer Over-read in ASN.1 Content Parsing
    30Monitor
  • CVE-2026-907663 days apartOut-of-Bounds Read in CMS Password-Based Decryption
    30Monitor
  • CVE-2025-9230189 days apartOut-of-bounds read & write in RFC 3211 KEK Unwrap
    30Monitor
  • CVE-2026-4277163 days apartPossible Out of Bounds Read in X509_VERIFY_PARAM_set1_email()
    24Monitor
  • CVE-2025-9232189 days apartOut-of-bounds read in HTTP client no_proxy handling
    24Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records