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NVD / CVE Program· CNA openssl

CVE-2026-63072: Heap Buffer Overflow in CMS Key Unwrapping

Noroxi assessment

Priority: Monitor (action score 30/100)

  • Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.91% (FIRST EPSS); higher than 60.4% of all records.
  • 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 3.0.22, 3.4.7, 3.5.8; azl3 edk2 20240524git3e722403cd16-18 on Azure Linux 3.0 20240524git3e722403cd16-19; azl3 edk2 20240524git3e722403cd16-20 on Azure Linux 3.0 20240524git3e722403cd16-19.

Low priority for now. Upgrade to OpenSSL OpenSSL 3.0.22, 3.4.7, 3.5.8; azl3 edk2 20240524git3e722403cd16-18 on Azure Linux 3.0 20240524git3e722403cd16-19; azl3 edk2 20240524git3e722403cd16-20 on Azure Linux 3.0 20240524git3e722403cd16-19 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: OpenSSL CMS decryption sizes the key-unwrap output buffer based on querying the unwrapped key size, but the AES-WRAP-PAD unwrap primitive can write and cleanse more bytes than that query reports, causing an 8-byte out-of-bounds heap write. Impact summary: An attacker who supplies a crafted CMS message can trigger a deterministic 8-byte out-of-bounds heap write when the victim decrypts it with CMS_decrypt(), corrupting the heap and typically resulting in a Denial of Service. CWE: CWE-787: Out-of-bounds Write Description: The key-wrap OID is potentially attacker-controlled on the wire. CMS unwrapping allows both id-aesNNN-wrap-pad and id-aesNNN-wrap ciphers. An attacker can take a legitimate message and change a single OID byte to select the padded variant while leaving the message otherwise valid. Since the unwrap key is derived from the recipient's private operation (ECDH key agreement or ML-KEM decapsulation), the RFC 5649 integrity check cannot pass, and the decryption fails with integrity failure. The write is a fixed-size (8-byte), fixed-value (zero) heap overflow immediately past the allocation, requires no special configuration, and is reachable from the public CMS_decrypt() function. The consequence is a heap corruption leading to a Denial of Service. The fix in the CMS code sizes the unwrap output buffer for the worst case so a failed unwrap cannot write past the allocation. FIPS impact: no As the CMS code lives outside the FIPS module boundary, no FIPS modules are affected by this CVE.

HighCVSS 7.5 · v3.1—Proof of concept Fix available
Published
Aug 25, 2026
Updated
Sep 11, 2026
EPSS
0.9% · 60th 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 · 0.9%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

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  • Not in KEV: no record of exploitation in the wild
  • Proof of concept exists, no weaponized module
  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

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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 openssl3.0.0 and later · before 3.0.22
  • openssl openssl3.4.0 and later · before 3.4.7
  • openssl openssl3.5.0 and later · before 3.5.8
  • openssl openssl3.6.0 and later · before 3.6.4
  • openssl openssl4.0.0 and later · before 4.0.2

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

    • 4.0.0 and later · before 4.0.2affected · semver
    • 3.6.0 and later · before 3.6.4affected · semver
    • 3.5.0 and later · before 3.5.8affected · semver
    • 3.4.0 and later · before 3.4.7affected · semver
    • 3.0.0 and later · before 3.0.22affected · semver
    • 1.1.1 and later · before 1.1.1ziaffected

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10opensslbefore 1:3.5.8-1.el10_2.alma.11:3.5.8-1.el10_2.alma.1
AlmaLinux:10openssl-develbefore 1:3.5.8-1.el10_2.alma.11:3.5.8-1.el10_2.alma.1
AlmaLinux:10openssl-libsbefore 1:3.5.8-1.el10_2.alma.11:3.5.8-1.el10_2.alma.1
AlmaLinux:10openssl-perlbefore 1:3.5.8-1.el10_2.alma.11:3.5.8-1.el10_2.alma.1
AlmaLinux:8opensslbefore 1:1.1.1k-18.el8_61:1.1.1k-18.el8_6
AlmaLinux:8openssl-develbefore 1:1.1.1k-18.el8_61:1.1.1k-18.el8_6
AlmaLinux:8openssl-libsbefore 1:1.1.1k-18.el8_61:1.1.1k-18.el8_6
AlmaLinux:8openssl-perlbefore 1:1.1.1k-18.el8_61:1.1.1k-18.el8_6
AlmaLinux:9compat-openssl11before 1:1.1.1k-5.el9_8.61:1.1.1k-5.el9_8.6
AlmaLinux:9opensslbefore 1:3.5.8-1.el9_81:3.5.8-1.el9_8
AlmaLinux:9openssl-develbefore 1:3.5.8-1.el9_81:3.5.8-1.el9_8
AlmaLinux:9openssl-libsbefore 1:3.5.8-1.el9_81:3.5.8-1.el9_8
AlmaLinux:9openssl-perlbefore 1:3.5.8-1.el9_81:3.5.8-1.el9_8
Alpine:v3.21opensslfrom 3.0.0 · before 3.3.7-r13.3.7-r1
Alpine:v3.22opensslfrom 3.0.0 · before 3.5.8-r03.5.8-r0
Debian:12opensslbefore 3.0.22-1~deb12u13.0.22-1~deb12u1
Debian:13opensslbefore 3.5.7-1~deb13u23.5.7-1~deb13u2
Debian:14opensslbefore 3.6.4-13.6.4-1
openSUSE:Leap 16.0openssl-3before 3.5.0-160000.10.13.5.0-160000.10.1
openSUSE:Tumbleweedopenssl-3before 3.5.3-8.13.5.3-8.1
Red Hat:enterprise_linux:10.2opensslbefore 1:3.5.8-1.el10_21:3.5.8-1.el10_2
Red Hat:enterprise_linux:10.2openssl-debuginfobefore 1:3.5.8-1.el10_21:3.5.8-1.el10_2
Red Hat:enterprise_linux:10.2openssl-debugsourcebefore 1:3.5.8-1.el10_21:3.5.8-1.el10_2
Red Hat:enterprise_linux:10.2openssl-develbefore 1:3.5.8-1.el10_21:3.5.8-1.el10_2

+52

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…KEV
    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-2026-18798Aug 25, 2026 · QUIC Server May Trigger Double Free When Processing INITIAL Packet
    31Monitor
  • ← EarlierCVE-2026-54874Aug 25, 2026 · Excessive Memory Use Buffering DTLS Records for a Future Epoch
    30Monitor
  • Later →CVE-2026-63073Aug 25, 2026 · Untrusted Sender DN Used as Format String in CMP Response Validation
    39Monitor

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 OpenSSL3.0.22Vendor (CNA)
OpenSSL OpenSSL3.4.7Vendor (CNA)
OpenSSL OpenSSL3.5.8Vendor (CNA)
OpenSSL OpenSSL3.6.4Vendor (CNA)
OpenSSL OpenSSL4.0.2Vendor (CNA)
azl3 edk2 20240524git3e722403cd16-18 on Azure Linux 3.020240524git3e722403cd16-19Microsoft (MSRC)
azl3 edk2 20240524git3e722403cd16-20 on Azure Linux 3.020240524git3e722403cd16-19Microsoft (MSRC)
azl3 openssl 3.3.7-4 on Azure Linux 3.03.3.7-6Microsoft (MSRC)
azl3 openssl 3.3.7-6 on Azure Linux 3.03.3.7-6Microsoft (MSRC)
almalinux:compat-openssl111:1.1.1k-5.el9_8.6 · AlmaLinux:9Package registry (OSV)
almalinux:openssl1:3.5.8-1.el10_2.alma.1 · AlmaLinux:10Package registry (OSV)
almalinux:openssl-devel1:3.5.8-1.el10_2.alma.1 · AlmaLinux:10Package registry (OSV)
almalinux:openssl-libs1:3.5.8-1.el10_2.alma.1 · AlmaLinux:10Package registry (OSV)
almalinux:openssl-perl1:3.5.8-1.el10_2.alma.1 · AlmaLinux:10Package registry (OSV)
alpine:openssl3.3.7-r1 · Alpine:v3.21Package registry (OSV)
debian:openssl3.0.22-1~deb12u1 · Debian:12Package registry (OSV)
opensuse:openssl-33.5.3-8.1 · openSUSE:TumbleweedPackage registry (OSV)
red hat:openssl0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-config-fips0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-debuginfo1:3.5.8-1.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:openssl-devel0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-devel-engine0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-fips-provider-upstream0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-libs0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-perl0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl30:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl3-devel0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl3-devel-engine0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl3-libs0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
rocky linux:compat-openssl111:1.1.1k-5.el9_8.6 · Rocky Linux:9Package registry (OSV)

+6

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

  • Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
SourceKindDate
Proof-of-concept repository on GitHubstars:02026-08-26

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.

  1. Published
  2. First PoC+1 d
  3. TodayNov 11, 2026+78 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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-2025-15467210 days apartStack buffer overflow in CMS (Auth)EnvelopedData parsing
    57Plan
  • CVE-2026-31789140 days apartHeap Buffer Overflow in Hexadecimal Conversion
    39Monitor
  • CVE-2026-738377 days apartPossible Heap Buffer Overflow in ASN.1 Multibyte String Conversion
    32Monitor
  • CVE-2026-7289735 days apartOut-of-Bounds Access After SSL_set_SSL_CTX() During a Handshake
    30Monitor
  • CVE-2025-69419210 days apartOut of bounds write in PKCS12_get_friendlyname() UTF-8 conversion
    29Monitor
  • CVE-2025-68160210 days apartHeap out-of-bounds write in BIO_f_linebuffer on short writes
    18Monitor

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-787 · Out-of-bounds Write

CVSS vector

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

nvd-secondary

Attack context

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

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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

References

Show all references (5 more)

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

All records