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openssl — security advisory

Type: advisorySources: OSVAdvisory ID: ALPINE-CVE-2026-72897

Issue summary: A TLS server that calls SSL_set_SSL_CTX() to switch a connection to a different SSL_CTX part way through a handshake may access memory beyond the end of an internal array if the replacement context knows about more provider signature algorithms than the context the connection was created from. Applications which never call SSL_set_SSL_CTX() are not affected. Impact summary: A remote peer may be able to cause a small out-of-bounds read, and in some circumstances a fixed-value out-of-bounds write, on the server heap. This may lead to a Denial of Service. CWE: CWE-787: Out-of-bounds Write Description: A TLS connection records how many certificate slots it has when it is created, taken from the SSL_CTX that created it: the built-in certificate types plus one slot for each provider TLS-SIGALG entry that context was aware of. That count sizes an internal array of per-slot certificate validity flags. An application may replace a connection's SSL_CTX part way through the handshake by calling SSL_set_SSL_CTX(), most commonly from a servername callback in order to serve a different virtual host. Doing so did not refresh the recorded count. A provider signature algorithm's slot index is its position in the list of whichever context resolves it, so if the replacement context is aware of more of them than the original, an algorithm offered by the peer can resolve to an index beyond the end of the array. Processing the peer's signature algorithms then reads one four byte wor

Products
openssl
Affected versions
Not specified
Fixed versions
3.3.7-r2
CVEs
CVE-2026-72897
Confirmed fixed CVEs
Not specified
Updated in this feed
28 Oct 2026, 09:02 UTC · Revision 1

Source evidence

ALPINE-CVE-2026-72897

core-osv · Original source

Published 29 Sept 2026, 16:17 UTC

Issue summary: A TLS server that calls SSL_set_SSL_CTX() to switch a connection to a different SSL_CTX part way through a handshake may access memory beyond the end of an internal array if the replacement context knows about more provider signature algorithms than the context the connection was created from. Applications which never call SSL_set_SSL_CTX() are not affected. Impact summary: A remote peer may be able to cause a small out-of-bounds read, and in some circumstances a fixed-value out-of-bounds write, on the server heap. This may lead to a Denial of Service. CWE: CWE-787: Out-of-bounds Write Description: A TLS connection records how many certificate slots it has when it is created, taken from the SSL_CTX that created it: the built-in certificate types plus one slot for each provider TLS-SIGALG entry that context was aware of. That count sizes an internal array of per-slot certificate validity flags. An application may replace a connection's SSL_CTX part way through the handshake by calling SSL_set_SSL_CTX(), most commonly from a servername callback in order to serve a different virtual host. Doing so did not refresh the recorded count. A provider signature algorithm's slot index is its position in the list of whichever context resolves it, so if the replacement context is aware of more of them than the original, an algorithm offered by the peer can resolve to an index beyond the end of the array. Processing the peer's signature algorithms then reads one four byte wor

osv:ALPINE-CVE-2026-72897

openssl

Fixed versions: 3.3.7-r2

Complete source record
{
  "id": "bcf8ad63a5c6513ac8a548a277dc460c02fed473181a76d492361ebc26849b61",
  "url": "https://osv.dev/vulnerability/ALPINE-CVE-2026-72897",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ALPINE-CVE-2026-72897",
    "summary": "Issue summary: A TLS server that calls SSL_set_SSL_CTX() to switch a connection to a different SSL_CTX part way through a handshake may access memory beyond the end of an internal array if the replacement context knows about more provider signature algorithms than the context the connection was created from. Applications which never call SSL_set_SSL_CTX() are not affected. Impact summary: A remote peer may be able to cause a small out-of-bounds read, and in some circumstances a fixed-value out-of-bounds write, on the server heap. This may lead to a Denial of Service. CWE: CWE-787: Out-of-bounds Write Description: A TLS connection records how many certificate slots it has when it is created, taken from the SSL_CTX that created it: the built-in certificate types plus one slot for each provider TLS-SIGALG entry that context was aware of. That count sizes an internal array of per-slot certificate validity flags. An application may replace a connection's SSL_CTX part way through the handshake by calling SSL_set_SSL_CTX(), most commonly from a servername callback in order to serve a different virtual host. Doing so did not refresh the recorded count. A provider signature algorithm's slot index is its position in the list of whichever context resolves it, so if the replacement context is aware of more of them than the original, an algorithm offered by the peer can resolve to an index beyond the end of the array. Processing the peer's signature algorithms then reads one four byte wor",
    "evidence": "osv:ALPINE-CVE-2026-72897",
    "products": [
      {
        "name": {
          "value": "openssl",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "3.3.7-r2",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "ALPINE-CVE-2026-72897",
      "aliases": [
        "ALPINE-CVE-2026-72897"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "3.4.0"
                },
                {
                  "fixed": "3.3.7-r2"
                }
              ]
            }
          ],
          "package": {
            "name": "openssl",
            "purl": "pkg:apk/alpine/openssl?arch=source",
            "ecosystem": "Alpine:v3.21"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-72897.json"
          },
          "ecosystem_specific": {}
        }
      ],
      "modified": "2026-10-08T09:30:02.578624308Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-72897"
      ],
      "references": [
        "https://security.alpinelinux.org/vuln/CVE-2026-72897"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-72897",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 98845,
  "published_at": "2026-09-29T16:17:09.903+00:00"
}