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CVE.org (no NVD analysis yet)· CNA openssl

CVE-2026-84782: DTLS Retransmits Handshake Messages From a Stale Buffer Offset

HighCVSS 8.2 · v3.1—No exploit Fix available

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: 0.90% (FIRST EPSS); higher than 60.3% 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 3.0.23, 3.4.8, 3.5.9; azl3 edk2 20240524git3e722403cd16-20 on Azure Linux 3.0 20240524git3e722403cd16-21; azl3 openssl 3.3.7-6 on Azure Linux 3.0 3.3.7-7.

Low priority for now. Upgrade to OpenSSL OpenSSL 3.0.23, 3.4.8, 3.5.9; azl3 edk2 20240524git3e722403cd16-20 on Azure Linux 3.0 20240524git3e722403cd16-21; azl3 openssl 3.3.7-6 on Azure Linux 3.0 3.3.7-7 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: The DTLS retransmission logic does not correctly handle a handshake message write that is suspended part-way through. The retransmitted message can be read past the message buffer and the retransmission overwrites the internal state the suspended write needs to resume correctly. Impact summary: The retransmitted message can disclose a heap memory to the peer as plaintext handshake data or cause a crash and a Denial of Service when the read reaches an unmapped memory region. CWE: CWE-125: Out-of-bounds Read Description: DTLS handshake messages can be written out in multiple fragments, and a write can suspend mid-message (returning WANT_WRITE) if the underlying transport temporarily cannot accept more data. While such a write is suspended, the DTLS retransmission timer may independently fire and ask the retransmission logic to resend an earlier, already-acknowledged-as-sent message from its retransmit queue. The retransmission logic reused the same internal buffer and position tracking as the message that was still being written, without resetting the position back to the start of the message being retransmitted. As a result the retransmission was read starting from wherever the suspended write had left off, producing a mislabelled message whose body was leftover bytes from the other, larger message still in flight - content that was never meant to be sent at that point, and which could run past the end of the allocated buffer. Separately, even when the retransmission is positioned correctly, allowing it to run to completion while another write is suspended overwrites the same shared bookkeeping that the suspended write depends on to resume. When the application later resumes the suspended write (via a subsequent SSL_read(), SSL_write(), SSL_accept(), or SSL_connect() call), it finds that bookkeeping in a state inconsistent with the message and aborts the process in a debugging build. The fix resets the retransmission's read position to the start of the message before resending, and skips retransmission entirely whenever a handshake write is still suspended, deferring to the next call that resumes it instead. FIPS impact: no The affected code is outside the FIPS module boundary.

Published
Sep 29, 2026
Updated
Nov 10, 2026
EPSS
0.9% · 60th percentile

Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
32 / 40 · 8.2 / 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
  • No public exploit code on record
  • A fix has been released

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Affected systems

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VendorProduct
opensslopenssl

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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 4.0.3affected · semver
    • 3.6.0 and later · before 3.6.5affected · semver
    • 3.5.0 and later · before 3.5.9affected · semver
    • 3.4.0 and later · before 3.4.8affected · semver
    • 3.0.0 and later · before 3.0.23affected · semver
    • 1.1.1 and later · before 1.1.1zjaffected
    • 1.0.2 and later · before 1.0.2zsaffected
Affected versions · NVD (7)

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 1.0.2zs
  • openssl openssl1.1.1 and later · before 1.1.1zj
  • openssl openssl3.0.0 and later · before 3.0.23
  • openssl openssl3.4.0 and later · before 3.4.8
  • openssl openssl3.5.0 and later · before 3.5.9
  • openssl openssl3.6.0 and later · before 3.6.5
  • openssl openssl4.0.0 and later · before 4.0.3

Package-level exposure

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

EcosystemPackageAffected rangeFix
AlmaLinux:10opensslbefore 1:3.5.8-2.el10_2.alma.11:3.5.8-2.el10_2.alma.1
AlmaLinux:10openssl-develbefore 1:3.5.8-2.el10_2.alma.11:3.5.8-2.el10_2.alma.1
AlmaLinux:10openssl-libsbefore 1:3.5.8-2.el10_2.alma.11:3.5.8-2.el10_2.alma.1
AlmaLinux:10openssl-perlbefore 1:3.5.8-2.el10_2.alma.11:3.5.8-2.el10_2.alma.1
AlmaLinux:8compat-openssl10before 1:1.0.2o-4.el8_10.41:1.0.2o-4.el8_10.4
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 1:3.5.8-2.el9_81:3.5.8-2.el9_8
AlmaLinux:9openssl-develbefore 1:3.5.8-2.el9_81:3.5.8-2.el9_8
AlmaLinux:9openssl-libsbefore 1:3.5.8-2.el9_81:3.5.8-2.el9_8
AlmaLinux:9openssl-perlbefore 1:3.5.8-2.el9_81:3.5.8-2.el9_8
Alpine:v3.21opensslfrom 1.0.2 · before 3.3.7-r23.3.7-r2
Debian:12opensslbefore 3.0.22-1~deb12u23.0.22-1~deb12u2
Debian:13opensslbefore 3.5.7-1~deb13u33.5.7-1~deb13u3
Debian:14opensslbefore 3.6.5-13.6.5-1
openSUSE:Leap 16.0openssl-3before 3.5.0-160000.11.13.5.0-160000.11.1
Red Hat:enterprise_linux:10.2opensslbefore 1:3.5.8-2.el10_21:3.5.8-2.el10_2
Red Hat:enterprise_linux:10.2openssl-debuginfobefore 1:3.5.8-2.el10_21:3.5.8-2.el10_2
Red Hat:enterprise_linux:10.2openssl-debugsourcebefore 1:3.5.8-2.el10_21:3.5.8-2.el10_2
Red Hat:enterprise_linux:10.2openssl-develbefore 1:3.5.8-2.el10_21:3.5.8-2.el10_2
Red Hat:enterprise_linux:10.2openssl-libsbefore 1:3.5.8-2.el10_21:3.5.8-2.el10_2

+59

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-2026-75806Sep 29, 2026 · Unauthenticated and Undersized DTLS 1.2 AEAD Record Causes DoS
    21Monitor
  • ← EarlierCVE-2026-77696Sep 29, 2026 · Timing Side-Channel in SM2 Signature Generation
    14Monitor
  • Later →CVE-2026-84783Sep 29, 2026 · Use-After-Free in X.509 Extension Cache Under Concurrent Use
    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 OpenSSL3.0.23Vendor (CNA)
OpenSSL OpenSSL3.4.8Vendor (CNA)
OpenSSL OpenSSL3.5.9Vendor (CNA)
OpenSSL OpenSSL3.6.5Vendor (CNA)
OpenSSL OpenSSL4.0.3Vendor (CNA)
azl3 edk2 20240524git3e722403cd16-20 on Azure Linux 3.020240524git3e722403cd16-21 · Release NotesMicrosoft (MSRC)
azl3 openssl 3.3.7-6 on Azure Linux 3.03.3.7-7 · Release NotesMicrosoft (MSRC)
almalinux:compat-openssl101:1.0.2o-4.el8_10.4 · AlmaLinux:8Package registry (OSV)
almalinux:compat-openssl111:1.1.1k-5.el9_8.6 · AlmaLinux:9Package registry (OSV)
almalinux:openssl1:3.5.8-2.el10_2.alma.1 · AlmaLinux:10Package registry (OSV)
almalinux:openssl-devel1:3.5.8-2.el10_2.alma.1 · AlmaLinux:10Package registry (OSV)
almalinux:openssl-libs1:3.5.8-2.el10_2.alma.1 · AlmaLinux:10Package registry (OSV)
almalinux:openssl-perl1:3.5.8-2.el10_2.alma.1 · AlmaLinux:10Package registry (OSV)
alpine:openssl3.3.7-r2 · Alpine:v3.21Package registry (OSV)
debian:openssl3.0.22-1~deb12u2 · Debian:12Package registry (OSV)
debian:openssl3.5.7-1~deb13u3 · Debian:13Package registry (OSV)
opensuse:openssl-33.5.0-160000.11.1 · openSUSE:Leap 16.0Package registry (OSV)
red hat:bootupd0:0.3.2-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:chunkah0:0.7.0-1.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl0:3.5.9-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-config-fips0:3.5.9-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-devel0:3.5.9-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:ruby3.40:3.4.10-31.7.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:ruby3.4-bundled-gems0:3.4.10-31.7.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:ruby3.4-default-gems0:3.4.10-31.7.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:ruby3.4-devel0:3.4.10-31.7.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:ruby3.4-doc0:3.4.10-31.7.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:ruby3.4-libs0:3.4.10-31.7.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:rust-bootupd0:0.3.2-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
rocky linux:compat-openssl101:1.0.2o-4.el8_10.4 · Rocky Linux:8Package registry (OSV)

+9

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.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 13, 2026+45 d
EPSS, last 120 days+1% in 7 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-2025-9230364 days apartOut-of-bounds read & write in RFC 3211 KEK Unwrap
    40Plan
  • CVE-2026-34180112 days apartHeap Buffer Over-read in ASN.1 Content Parsing
    30Monitor
  • CVE-2026-9076112 days apartOut-of-Bounds Read in CMS Password-Based Decryption
    30Monitor
  • CVE-2026-28386175 days apartOut-of-bounds Read in AES-CFB-128 on X86-64 with AVX-512 Support
    30Monitor
  • CVE-2026-42771112 days apartPossible Out of Bounds Read in X509_VERIFY_PARAM_set1_email()
    24Monitor
  • CVE-2025-9232364 days apartOut-of-bounds read in HTTP client no_proxy handling
    24Monitor

Not on record for this CVE: public bounty program.

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
low · data can be read
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
Low
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:L/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.

ATT&CK techniques

—

Change log

  1. Exploit maturity— → none
  2. Fix✗ → ✓
  3. CVSS— → 8.2
  4. Severity— → high
  5. SSVC exploitation— → none

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