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NVD / CVE Program· CNA openssl

CVE-2026-7383: Possible Heap Buffer Overflow in ASN.1 Multibyte String Conversion

Noroxi assessment

Priority: Monitor (action score 32/100)

  • 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: 0.80% (FIRST EPSS); higher than 56.8% 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. Special conditions such as timing or configuration are required.
  • Fixed version: OpenSSL OpenSSL 3.0.21, 3.4.6, 3.5.7; azl3 edk2 20240524git3e722403cd16-17 on Azure Linux 3.0 20240524git3e722403cd16-18; azl3 openssl 3.3.5-5 on Azure Linux 3.0 3.3.7-3.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to OpenSSL OpenSSL 3.0.21, 3.4.6, 3.5.7; azl3 edk2 20240524git3e722403cd16-17 on Azure Linux 3.0 20240524git3e722403cd16-18; azl3 openssl 3.3.5-5 on Azure Linux 3.0 3.3.7-3 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: A signed integer overflow when sizing the destination buffer for Unicode output in ASN1_mbstring_ncopy() can lead to a heap buffer overflow. Impact summary: A heap buffer overflow may lead to a crash or possibly attacker controlled code execution or other undefined behaviour. In ASN1_mbstring_copy() and ASN1_mbstring_ncopy() the destination size for Unicode output is computed in a signed int: by left shift of the input character count for BMPSTRING (UTF-16) and UNIVERSALSTRING (UTF-32), and by summing per-character byte counts for UTF8STRING. The calculation overflows when the input reaches around 2^30 characters. In the worst case (UNIVERSALSTRING at 2^30 characters) the size wraps to zero, OPENSSL_malloc(1) is called, and the subsequent character copy writes several gigabytes past the one-byte allocation. X.509 certificate processing routes through ASN1_STRING_set_by_NID(), whose DIRSTRING_TYPE mask excludes UNIVERSALSTRING and whose per-NID size limits cap the input length; no network protocol or certificate-handling path in OpenSSL exercises the overflow. Triggering the bug requires an application that calls ASN1_mbstring_copy() or ASN1_mbstring_ncopy() directly, or registers a custom string type via ASN1_STRING_TABLE_add(), with attacker-controlled input on the order of half a gigabyte or more. For these reasons this issue was assigned Low severity. The FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by this issue, as the affected code is outside the OpenSSL FIPS module boundary.

HighCVSS 8.1 · v3.1—No exploit Fix available
Published
Jun 9, 2026
Updated
Jul 23, 2026
EPSS
0.8% · 56th percentile

Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
32 / 40 · 8.1 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.8%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

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

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  • when exploit code appears or is weaponized
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  • 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 openssl1.0.2 and later · before 1.0.2zq
  • openssl openssl1.1.1 and later · before 1.1.1zh
  • openssl openssl3.0.0 and later · before 3.0.21
  • openssl openssl3.4.0 and later · before 3.4.6
  • openssl openssl3.5.0 and later · before 3.5.7
  • openssl openssl3.6.0 and later · before 3.6.3
  • openssl openssl4.0.0

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 4.0.1affected · semver
    • 3.6.0 and later · before 3.6.3affected · semver
    • 3.5.0 and later · before 3.5.7affected · semver
    • 3.4.0 and later · before 3.4.6affected · semver
    • 3.0.0 and later · before 3.0.21affected · semver
    • 1.1.1 and later · before 1.1.1zhaffected
    • 1.0.2 and later · before 1.0.2zqaffected

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10opensslbefore 1:3.5.5-4.el10_2.alma.11:3.5.5-4.el10_2.alma.1
AlmaLinux:10openssl-develbefore 1:3.5.5-4.el10_2.alma.11:3.5.5-4.el10_2.alma.1
AlmaLinux:10openssl-libsbefore 1:3.5.5-4.el10_2.alma.11:3.5.5-4.el10_2.alma.1
AlmaLinux:10openssl-perlbefore 1:3.5.5-4.el10_2.alma.11:3.5.5-4.el10_2.alma.1
AlmaLinux:9opensslbefore 1:3.5.5-4.el9_81:3.5.5-4.el9_8
AlmaLinux:9openssl-develbefore 1:3.5.5-4.el9_81:3.5.5-4.el9_8
AlmaLinux:9openssl-libsbefore 1:3.5.5-4.el9_81:3.5.5-4.el9_8
AlmaLinux:9openssl-perlbefore 1:3.5.5-4.el9_81:3.5.5-4.el9_8
Alpine:v3.22opensslfrom 1.0.2 · before 3.5.7-r03.5.7-r0
Debian:12opensslbefore 3.0.20-1~deb12u23.0.20-1~deb12u2
Debian:13opensslbefore 3.5.6-1~deb13u23.5.6-1~deb13u2
Debian:14opensslbefore 3.6.3-13.6.3-1
openSUSE:Leap 16.0openssl-3before 3.5.0-160000.8.13.5.0-160000.8.1
openSUSE:Tumbleweedopenssl-3before 3.5.3-6.13.5.3-6.1
Red Hat:enterprise_linux:10.2opensslbefore 1:3.5.5-4.el10_21:3.5.5-4.el10_2
Red Hat:enterprise_linux:10.2openssl-debuginfobefore 1:3.5.5-4.el10_21:3.5.5-4.el10_2
Red Hat:enterprise_linux:10.2openssl-debugsourcebefore 1:3.5.5-4.el10_21:3.5.5-4.el10_2
Red Hat:enterprise_linux:10.2openssl-develbefore 1:3.5.5-4.el10_21:3.5.5-4.el10_2
Red Hat:enterprise_linux:10.2openssl-libsbefore 1:3.5.5-4.el10_21:3.5.5-4.el10_2
Red Hat:enterprise_linux:10.2openssl-libs-debuginfobefore 1:3.5.5-4.el10_21:3.5.5-4.el10_2
Red Hat:enterprise_linux:10.2openssl-perlbefore 1:3.5.5-4.el10_21:3.5.5-4.el10_2
Red Hat:enterprise_linux:9::appstreamopenssl-debuginfobefore 1:3.5.5-4.el9_81:3.5.5-4.el9_8
Red Hat:enterprise_linux:9::appstreamopenssl-debugsourcebefore 1:3.5.5-4.el9_81:3.5.5-4.el9_8
Red Hat:enterprise_linux:9::appstreamopenssl-develbefore 1:3.5.5-4.el9_81:3.5.5-4.el9_8

+77

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-2026-45446Jun 9, 2026 · Incorrect Tag Processing for Empty Messages in AES-GCM-SIV and AES-SIV modes
    19Monitor
  • ← EarlierCVE-2026-45447Jun 9, 2026 · Heap Use-After-Free in the PKCS7_verify() Function
    36Monitor
  • Later →CVE-2026-9076Jun 9, 2026 · Out-of-Bounds Read in CMS Password-Based Decryption
    30Monitor

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 OpenSSL3.0.21Vendor (CNA)
OpenSSL OpenSSL3.4.6Vendor (CNA)
OpenSSL OpenSSL3.5.7Vendor (CNA)
OpenSSL OpenSSL3.6.3Vendor (CNA)
OpenSSL OpenSSL4.0.1Vendor (CNA)
azl3 edk2 20240524git3e722403cd16-17 on Azure Linux 3.020240524git3e722403cd16-18 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 openssl 3.3.5-5 on Azure Linux 3.03.3.7-3 · CBL-Mariner ReleasesMicrosoft (MSRC)
almalinux:openssl1:3.5.5-4.el10_2.alma.1 · AlmaLinux:10Package registry (OSV)
almalinux:openssl-devel1:3.5.5-4.el10_2.alma.1 · AlmaLinux:10Package registry (OSV)
almalinux:openssl-libs1:3.5.5-4.el10_2.alma.1 · AlmaLinux:10Package registry (OSV)
almalinux:openssl-perl1:3.5.5-4.el10_2.alma.1 · AlmaLinux:10Package registry (OSV)
alpine:openssl3.5.7-r0 · Alpine:v3.22Package registry (OSV)
debian:openssl3.0.20-1~deb12u2 · Debian:12Package registry (OSV)
opensuse:openssl-33.5.3-6.1 · openSUSE:TumbleweedPackage registry (OSV)
red hat:chunkah0:0.6.0-3.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl1:3.5.5-4.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:openssl-debuginfo1:3.5.5-4.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:openssl-debugsource1:3.5.5-4.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:openssl-devel1:3.5.5-4.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:openssl-libs1:3.5.5-4.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:openssl-libs-debuginfo1:3.5.5-4.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:openssl-perl1:3.5.5-4.el10_2 · Red Hat:enterprise_linux:10.2Package registry (OSV)
red hat:ruby3.30:3.3.10-23.6.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:ruby3.3-bundled-gems0:3.3.10-23.6.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:ruby3.3-default-gems0:3.3.10-23.6.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:ruby3.3-devel0:3.3.10-23.6.hum1 · Red Hat:hummingbird:1Package registry (OSV)
rocky linux:openssl1:3.5.5-4.el10_2 · Rocky Linux:10Package registry (OSV)
suse:openssl-1_0_01.0.2p-3.109.1 · SUSE:Linux Enterprise Server 12 SP5-LTSSPackage registry (OSV)
suse:openssl-1_11.1.1w-150700.11.22.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP7Package registry (OSV)
suse:openssl-33.1.4-14.1 · SUSE:Linux Micro 6.0Package 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-2025-15467133 days apartStack buffer overflow in CMS (Auth)EnvelopedData parsing
    57Plan
  • CVE-2026-3178963 days apartHeap Buffer Overflow in Hexadecimal Conversion
    39Monitor
  • CVE-2026-6307277 days apartHeap Buffer Overflow in CMS Key Unwrapping
    30Monitor
  • CVE-2026-72897112 days apartOut-of-Bounds Access After SSL_set_SSL_CTX() During a Handshake
    30Monitor
  • CVE-2025-69419133 days apartOut of bounds write in PKCS12_get_friendlyname() UTF-8 conversion
    29Monitor
  • CVE-2025-68160133 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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

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.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-787 · Out-of-bounds Write

CVSS vector

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