Vulnerability-Lookup

RHSA-2026:99724

Vulnerability from csaf_redhat - Published: 2026-11-12 18:48 - Updated: 2026-11-13 00:02

Summary

Red Hat Security Advisory: compat-openssl10 security update

Severity

Important

Notes

Topic: An update for compat-openssl10 is now available for Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions and Red Hat Enterprise Linux 8.8 Telecommunications Update Service. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Details: The OpenSSL toolkit provides support for secure communications between machines. This version of OpenSSL package contains only the libraries and is provided for compatibility with previous releases and software that does not support compilation with OpenSSL-1.1. Security Fix(es): * openssl: compat-openssl: DTLS Retransmits Handshake Messages From a Stale Buffer Offset (CVE-2026-84782) For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Terms of Use: This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original.

CVE-2026-84782

A flaw was found in OpenSSL. The Datagram Transport Layer Security (DTLS) retransmission mechanism fails to properly handle handshake message writes that are suspended before completion. A remote attacker could exploit this vulnerability during handshake message retransmission, causing OpenSSL to read past the message buffer or overwrite internal state required to resume writing. This issue can result in information disclosure through out-of-bounds memory reads or cause a Denial of Service (DoS) by crashing the process.

7.4 (High)


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

CWE-125 - Out-of-bounds Read

Affected products

Fixed 17 products

Product	Version	Remediation
Unresolved product id: AppStream-8.8.0.Z.E4S:compat-openssl10-1:1.0.2o-4.el8_8.2.i686	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.E4S:compat-openssl10-1:1.0.2o-4.el8_8.2.ppc64le	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.E4S:compat-openssl10-1:1.0.2o-4.el8_8.2.src	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.E4S:compat-openssl10-1:1.0.2o-4.el8_8.2.x86_64	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.E4S:compat-openssl10-debuginfo-1:1.0.2o-4.el8_8.2.i686	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.E4S:compat-openssl10-debuginfo-1:1.0.2o-4.el8_8.2.ppc64le	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.E4S:compat-openssl10-debuginfo-1:1.0.2o-4.el8_8.2.x86_64	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.E4S:compat-openssl10-debugsource-1:1.0.2o-4.el8_8.2.i686	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.E4S:compat-openssl10-debugsource-1:1.0.2o-4.el8_8.2.ppc64le	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.E4S:compat-openssl10-debugsource-1:1.0.2o-4.el8_8.2.x86_64	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.TUS:compat-openssl10-1:1.0.2o-4.el8_8.2.i686	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.TUS:compat-openssl10-1:1.0.2o-4.el8_8.2.src	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.TUS:compat-openssl10-1:1.0.2o-4.el8_8.2.x86_64	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.TUS:compat-openssl10-debuginfo-1:1.0.2o-4.el8_8.2.i686	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.TUS:compat-openssl10-debuginfo-1:1.0.2o-4.el8_8.2.x86_64	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.TUS:compat-openssl10-debugsource-1:1.0.2o-4.el8_8.2.i686	—	Vendor Fix fix
Unresolved product id: AppStream-8.8.0.Z.TUS:compat-openssl10-debugsource-1:1.0.2o-4.el8_8.2.x86_64	—	Vendor Fix fix

Threats

Impact Important

References

9 references

URL	Category
https://access.redhat.com/errata/RHSA-2026:99724	self
https://access.redhat.com/security/updates/classi…	external
https://bugzilla.redhat.com/show_bug.cgi?id=2537080	external
https://security.access.redhat.com/data/csaf/v2/a…	self
https://access.redhat.com/security/cve/CVE-2026-84782	self
https://bugzilla.redhat.com/show_bug.cgi?id=2537080	external
https://www.cve.org/CVERecord?id=CVE-2026-84782	external
https://nvd.nist.gov/vuln/detail/CVE-2026-84782	external
https://openssl-library.org/news/vulnerabilities/…	external

JSON

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  "vulnerabilities": [
    {
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      "cwe": {
        "id": "CWE-125",
        "name": "Out-of-bounds Read"
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      "discovery_date": "2026-09-18T19:58:21.939000+00:00",
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          "text": "2537080"
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          "title": "Vulnerability description"
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          "text": "openssl: compat-openssl: openssl: Information disclosure via DTLS handshake retransmission",
          "title": "Vulnerability summary"
        },
        {
          "category": "other",
          "text": "This vulnerability is rated as an Important severity because an unauthenticated network adversary can trigger process crashes or memory exposure without requiring local system privileges. Red Hat Enterprise Linux utilizes OpenSSL as the fundamental cryptographic provider across the operating system; however, overall exposure is limited because the flaw strictly affects software using Datagram Transport Layer Security (DTLS) over UDP under non-blocking I/O configurations. Standard TLS connections over TCP, which represent the typical deployment model for the majority of Red Hat workloads and system services, are unaffected.",
          "title": "Statement"
        },
        {
          "category": "general",
          "text": "The CVSS score(s) listed for this vulnerability do not reflect the associated product\u0027s status, and are included for informational purposes to better understand the severity of this vulnerability.",
          "title": "CVSS score applicability"
        }
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        {
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  ]
}

CVE-2026-84782 (GCVE-0-2026-84782)

Vulnerability from cvelistv5 – Published: 2026-09-29 15:32 – Updated: 2026-11-10 12:49

Title

DTLS Retransmits Handshake Messages From a Stale Buffer Offset

Summary

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.

Severity

8.2 (High)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-29 16:45 UTC

CWE

CWE-125 - Out-of-bounds Read

Assigner

openssl CNA under the mitre root

CNA scorecard B 78/100 over 48 records in the last 180 days details

References

6 references

URL	Tags
https://openssl-library.org/news/secadv/20260929.txt	vendor-advisory
https://github.com/openssl/openssl/commit/d951e02…	patch
https://github.com/openssl/openssl/commit/a383daf…	patch
https://github.com/openssl/openssl/commit/906cf0e…	patch
https://github.com/openssl/openssl/commit/9f6b344…	patch
https://cert-portal.siemens.com/productcert/html/…

Impacted products

6 products

Vendor	Product	Version
OpenSSL	OpenSSL	Affected: 4.0.0 , < 4.0.3 (semver) Affected: 3.6.0 , < 3.6.5 (semver) Affected: 3.5.0 , < 3.5.9 (semver) Affected: 3.4.0 , < 3.4.8 (semver) Affected: 3.0.0 , < 3.0.23 (semver) Affected: 1.1.1 , < 1.1.1zj (custom) Affected: 1.0.2 , < 1.0.2zs (custom)
Siemens	SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)	Affected: V3.1.7 , < * (custom)
Siemens	SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)	Affected: V3.1.7 , < * (custom)
Siemens	SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)	Affected: V3.1.7 , < * (custom)
Siemens	SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)	Affected: V3.1.7 , < * (custom)
Siemens	SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)	Affected: V3.1.7 , < * (custom)

Date Public

2026-09-29 14:21

Credits

Laurent Gaffie (secorizon.com) Ryan Hooper

Show details on NVD website

JSON

To clipboard

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          "value": "Laurent Gaffie (secorizon.com)"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Ryan Hooper"
        }
      ],
      "datePublic": "2026-09-29T14:21:57.000Z",
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "Issue summary: The DTLS retransmission logic does not correctly handle\u003cbr\u003ea handshake message write that is suspended part-way through.\u003cbr\u003eThe retransmitted message can be read past the message buffer and\u003cbr\u003ethe retransmission overwrites the internal state the suspended write\u003cbr\u003eneeds to resume correctly.\u003cbr\u003e\u003cbr\u003eImpact summary: The retransmitted message can disclose a heap memory\u003cbr\u003eto the peer as plaintext handshake data or cause a crash and a Denial\u003cbr\u003eof Service when the read reaches an unmapped memory region.\u003cbr\u003e\u003cbr\u003eCWE: CWE-125: Out-of-bounds Read\u003cbr\u003e\u003cbr\u003eDescription: DTLS handshake messages can be written out in multiple\u003cbr\u003efragments, and a write can suspend mid-message (returning WANT_WRITE)\u003cbr\u003eif the underlying transport temporarily cannot accept more data. While\u003cbr\u003esuch a write is suspended, the DTLS retransmission timer may\u003cbr\u003eindependently fire and ask the retransmission logic to resend an\u003cbr\u003eearlier, already-acknowledged-as-sent message from its retransmit\u003cbr\u003equeue.\u003cbr\u003e\u003cbr\u003eThe retransmission logic reused the same internal buffer and position\u003cbr\u003etracking as the message that was still being written, without\u003cbr\u003eresetting the position back to the start of the message being\u003cbr\u003eretransmitted. As a result the retransmission was read starting from\u003cbr\u003ewherever the suspended write had left off, producing a mislabelled\u003cbr\u003emessage whose body was leftover bytes from the other, larger message\u003cbr\u003estill in flight - content that was never meant to be sent at that\u003cbr\u003epoint, and which could run past the end of the allocated buffer.\u003cbr\u003e\u003cbr\u003eSeparately, even when the retransmission is positioned correctly,\u003cbr\u003eallowing it to run to completion while another write is suspended\u003cbr\u003eoverwrites the same shared bookkeeping that the suspended write\u003cbr\u003edepends on to resume. When the application later resumes the\u003cbr\u003esuspended write (via a subsequent SSL_read(), SSL_write(),\u003cbr\u003eSSL_accept(), or SSL_connect() call), it finds that bookkeeping in a\u003cbr\u003estate inconsistent with the message and aborts the process in\u003cbr\u003ea debugging build.\u003cbr\u003e\u003cbr\u003eThe fix resets the retransmission\u0027s read position to the start of the\u003cbr\u003emessage before resending, and skips retransmission entirely whenever a\u003cbr\u003ehandshake write is still suspended, deferring to the next call that\u003cbr\u003eresumes it instead.\u003cbr\u003e\u003cbr\u003eFIPS impact: no\u003cbr\u003eThe affected code is outside the FIPS module boundary."
            }
          ],
          "value": "Issue summary: The DTLS retransmission logic does not correctly handle\na handshake message write that is suspended part-way through.\nThe retransmitted message can be read past the message buffer and\nthe retransmission overwrites the internal state the suspended write\nneeds to resume correctly.\n\nImpact summary: The retransmitted message can disclose a heap memory\nto the peer as plaintext handshake data or cause a crash and a Denial\nof Service when the read reaches an unmapped memory region.\n\nCWE: CWE-125: Out-of-bounds Read\n\nDescription: DTLS handshake messages can be written out in multiple\nfragments, and a write can suspend mid-message (returning WANT_WRITE)\nif the underlying transport temporarily cannot accept more data. While\nsuch a write is suspended, the DTLS retransmission timer may\nindependently fire and ask the retransmission logic to resend an\nearlier, already-acknowledged-as-sent message from its retransmit\nqueue.\n\nThe retransmission logic reused the same internal buffer and position\ntracking as the message that was still being written, without\nresetting the position back to the start of the message being\nretransmitted. As a result the retransmission was read starting from\nwherever the suspended write had left off, producing a mislabelled\nmessage whose body was leftover bytes from the other, larger message\nstill in flight - content that was never meant to be sent at that\npoint, and which could run past the end of the allocated buffer.\n\nSeparately, even when the retransmission is positioned correctly,\nallowing it to run to completion while another write is suspended\noverwrites the same shared bookkeeping that the suspended write\ndepends on to resume. When the application later resumes the\nsuspended write (via a subsequent SSL_read(), SSL_write(),\nSSL_accept(), or SSL_connect() call), it finds that bookkeeping in a\nstate inconsistent with the message and aborts the process in\na debugging build.\n\nThe fix resets the retransmission\u0027s read position to the start of the\nmessage before resending, and skips retransmission entirely whenever a\nhandshake write is still suspended, deferring to the next call that\nresumes it instead.\n\nFIPS impact: no\nThe affected code is outside the FIPS module boundary."
        }
      ],
      "metrics": [
        {
          "format": "other",
          "other": {
            "content": {
              "text": "High"
            },
            "type": "https://openssl-library.org/policies/general/security-policy/"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-125",
              "description": "CWE-125 Out-of-bounds Read",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-29T15:32:23.605Z",
        "orgId": "3a12439a-ef3a-4c79-92e6-6081a721f1e5",
        "shortName": "openssl"
      },
      "references": [
        {
          "name": "OpenSSL Advisory",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://openssl-library.org/news/secadv/20260929.txt"
        },
        {
          "name": "4.0.3 git commit",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/openssl/openssl/commit/d951e02ede8f6a6ff8150546db44b34f0518192c"
        },
        {
          "name": "3.6.5 git commit",
          "tags": [
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          ],
          "url": "https://github.com/openssl/openssl/commit/a383dafdd754eb5b22bf45e37e1bff9d07277a58"
        },
        {
          "name": "3.5.9 git commit",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/openssl/openssl/commit/906cf0ef1c85ca40ce69163e9086d6d3fe292943"
        },
        {
          "name": "3.4.8 git commit",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/openssl/openssl/commit/9f6b34422af7eb5dac61322e33dac1ae989fa628"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "DTLS Retransmits Handshake Messages From a Stale Buffer Offset",
      "x_generator": {
        "engine": "Vulnogram 0.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "3a12439a-ef3a-4c79-92e6-6081a721f1e5",
    "assignerShortName": "openssl",
    "cveId": "CVE-2026-84782",
    "datePublished": "2026-09-29T15:32:23.605Z",
    "dateReserved": "2026-09-02T10:14:02.262Z",
    "dateUpdated": "2026-11-10T12:49:53.213Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Publication & reservation Sightings KEV catalogs Other timestamps

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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