OESA-2026-2750 (CVE-2026-34180)

Vulnerability from osv_openeuler – Published: 2026-06-24 11:11 – Updated: 2026-08-06 11:11 – Source website
VLAI
Summary
shim security update
Details

Initial UEFI bootloader that handles chaining to a trusted full \ bootloader under secure boot environments.

Security Fix(es):

Issue summary: Parsing a crafted DER-encoded ASN.1 structure with a primitive element whose content exceeds 2 gigabytes in length may cause a heap buffer over-read on 64-bit Unix and Unix-like platforms.

Impact summary: The heap buffer over-read may crash the application (Denial of Service) or to load into the decoded ASN.1 object contents of memory beyond the end of the input buffer. More typically such ASN.1 elements would instead be truncated.

An integer truncation in OpenSSL's ASN.1 decoder causes the content length of an ASN.1 primitive element to be mishandled when it exceeds 2 gigabytes. In the worst case the truncated length is treated as a request to scan the binary content for a terminating zero byte, possibly causing OpenSSL to read either less than or beyond the end of the allocated buffer.

Applications that pass attacker-supplied data to d2i_X509(), d2i_PKCS7(), or any other d2i_* decoding function are affected. OpenSSL's own command-line tools are not vulnerable, as data read through the BIO layer is checked before it reaches the affected code. The issue only affects 64-bit Unix and Unix-like platforms; 32-bit platforms and 64-bit Windows are not affected.

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.(CVE-2026-34180)

Issue summary: A specially crafted PKCS#7 or S/MIME signed message could trigger a use-after-free during PKCS#7 signature verification.

Impact summary: A use-after-free may result in process crashes, heap corruption, or potentially remote code execution.

When processing a PKCS#7 or S/MIME signed message, if the SignedData digestAlgorithms field is present as an empty ASN.1 SET, OpenSSL may incorrectly free a caller-owned BIO during PKCS7_verify(). A subsequent use of the BIO by the calling application results in a use-after-free condition.

In the common case this occurs when the application later calls BIO_free() on the BIO originally passed to PKCS7_verify(). Depending on allocator behavior and application-specific BIO usage patterns, this may result in a crash or other memory corruption. In some application contexts this may potentially be exploitable for remote code execution.

Applications that process PKCS#7 or S/MIME signed messages using OpenSSL PKCS#7 APIs may be affected. Applications using the CMS APIs for this processing are not affected.

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.(CVE-2026-45447)

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.(CVE-2026-7383)

Severity
8.8 (High)
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
To clipboard 

{
  "affected": [
    {
      "ecosystem_specific": {
        "aarch64": [
          "shim-15.7-27.oe2403sp3.aarch64.rpm",
          "shim-debuginfo-15.7-27.oe2403sp3.aarch64.rpm",
          "shim-debugsource-15.7-27.oe2403sp3.aarch64.rpm",
          "shim-signed-15.7-27.oe2403sp3.aarch64.rpm"
        ],
        "src": [
          "shim-15.7-27.oe2403sp3.src.rpm"
        ],
        "x86_64": [
          "shim-15.7-27.oe2403sp3.x86_64.rpm",
          "shim-debuginfo-15.7-27.oe2403sp3.x86_64.rpm",
          "shim-debugsource-15.7-27.oe2403sp3.x86_64.rpm",
          "shim-signed-15.7-27.oe2403sp3.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:24.03-LTS-SP3",
        "name": "shim",
        "purl": "pkg:rpm/openEuler/shim\u0026distro=openEuler-24.03-LTS-SP3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "15.7-27.oe2403sp3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "aarch64": [
          "shim-15-42.oe2003sp4.aarch64.rpm"
        ],
        "noarch": [
          "shim-debuginfo-15-42.oe2003sp4.noarch.rpm",
          "shim-debugsource-15-42.oe2003sp4.noarch.rpm"
        ],
        "src": [
          "shim-15-42.oe2003sp4.src.rpm"
        ],
        "x86_64": [
          "shim-15-42.oe2003sp4.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:20.03-LTS-SP4",
        "name": "shim",
        "purl": "pkg:rpm/openEuler/shim\u0026distro=openEuler-20.03-LTS-SP4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "15-42.oe2003sp4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "aarch64": [
          "shim-15.6-31.oe2203sp4.aarch64.rpm",
          "shim-debuginfo-15.6-31.oe2203sp4.aarch64.rpm",
          "shim-debugsource-15.6-31.oe2203sp4.aarch64.rpm"
        ],
        "src": [
          "shim-15.6-31.oe2203sp4.src.rpm"
        ],
        "x86_64": [
          "shim-15.6-31.oe2203sp4.x86_64.rpm",
          "shim-debuginfo-15.6-31.oe2203sp4.x86_64.rpm",
          "shim-debugsource-15.6-31.oe2203sp4.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:22.03-LTS-SP4",
        "name": "shim",
        "purl": "pkg:rpm/openEuler/shim\u0026distro=openEuler-22.03-LTS-SP4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "15.6-31.oe2203sp4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "aarch64": [
          "shim-15.7-27.oe2403sp1.aarch64.rpm",
          "shim-debuginfo-15.7-27.oe2403sp1.aarch64.rpm",
          "shim-debugsource-15.7-27.oe2403sp1.aarch64.rpm",
          "shim-signed-15.7-27.oe2403sp1.aarch64.rpm"
        ],
        "src": [
          "shim-15.7-27.oe2403sp1.src.rpm"
        ],
        "x86_64": [
          "shim-15.7-27.oe2403sp1.x86_64.rpm",
          "shim-debuginfo-15.7-27.oe2403sp1.x86_64.rpm",
          "shim-debugsource-15.7-27.oe2403sp1.x86_64.rpm",
          "shim-signed-15.7-27.oe2403sp1.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:24.03-LTS-SP1",
        "name": "shim",
        "purl": "pkg:rpm/openEuler/shim\u0026distro=openEuler-24.03-LTS-SP1"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "15.7-27.oe2403sp1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "severity": "High"
  },
  "details": "Initial UEFI bootloader that handles chaining to a trusted full \\ bootloader under secure boot environments.\r\n\r\nSecurity Fix(es):\n\nIssue summary: Parsing a crafted DER-encoded ASN.1 structure with a primitive\nelement whose content exceeds 2 gigabytes in length may cause a heap buffer\nover-read on 64-bit Unix and Unix-like platforms.\n\nImpact summary: The heap buffer over-read may crash the application (Denial of\nService) or to load into the decoded ASN.1 object contents of memory beyond the\nend of the input buffer.  More typically such ASN.1 elements would instead be\ntruncated.\n\nAn integer truncation in OpenSSL\u0026apos;s ASN.1 decoder causes the content length of\nan ASN.1 primitive element to be mishandled when it exceeds 2 gigabytes. In the\nworst case the truncated length is treated as a request to scan the binary\ncontent for a terminating zero byte, possibly causing OpenSSL to read either\nless than or beyond the end of the allocated buffer.\n\nApplications that pass attacker-supplied data to d2i_X509(), d2i_PKCS7(), or\nany other d2i_* decoding function are affected. OpenSSL\u0026apos;s own command-line\ntools are not vulnerable, as data read through the BIO layer is checked before\nit reaches the affected code. The issue only affects 64-bit Unix and Unix-like\nplatforms; 32-bit platforms and 64-bit Windows are not affected.\n\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by this issue,\nas the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-34180)\n\nIssue summary: A specially crafted PKCS#7 or S/MIME signed message could\ntrigger a use-after-free during PKCS#7 signature verification.\n\nImpact summary: A use-after-free may result in process crashes, heap\ncorruption, or potentially remote code execution.\n\nWhen processing a PKCS#7 or S/MIME signed message, if the SignedData\ndigestAlgorithms field is present as an empty ASN.1 SET, OpenSSL may\nincorrectly free a caller-owned BIO during PKCS7_verify(). A subsequent\nuse of the BIO by the calling application results in a use-after-free\ncondition.\n\nIn the common case this occurs when the application later calls\nBIO_free() on the BIO originally passed to PKCS7_verify(). Depending\non allocator behavior and application-specific BIO usage patterns, this\nmay result in a crash or other memory corruption. In some application\ncontexts this may potentially be exploitable for remote code execution.\n\nApplications that process PKCS#7 or S/MIME signed messages using OpenSSL\nPKCS#7 APIs may be affected. Applications using the CMS APIs for this\nprocessing are not affected.\n\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this\nissue, as the affected code is outside the OpenSSL FIPS module boundary.(CVE-2026-45447)\n\nIssue summary: A signed integer overflow when sizing the destination\nbuffer for Unicode output in ASN1_mbstring_ncopy() can lead to a heap\nbuffer overflow.\n\nImpact summary: A heap buffer overflow may lead to a crash or possibly\nattacker controlled code execution or other undefined behaviour.\n\nIn ASN1_mbstring_copy() and ASN1_mbstring_ncopy() the destination\nsize for Unicode output is computed in a signed int: by left shift\nof the input character count for BMPSTRING (UTF-16) and\nUNIVERSALSTRING (UTF-32), and by summing per-character byte counts\nfor UTF8STRING. The calculation overflows when the input reaches\naround 2^30 characters. In the worst case (UNIVERSALSTRING at 2^30\ncharacters) the size wraps to zero, OPENSSL_malloc(1) is called, and\nthe subsequent character copy writes several gigabytes past the\none-byte allocation.\n\nX.509 certificate processing routes through ASN1_STRING_set_by_NID(),\nwhose DIRSTRING_TYPE mask excludes UNIVERSALSTRING and whose per-NID\nsize limits cap the input length; no network protocol or\ncertificate-handling path in OpenSSL exercises the overflow.\nTriggering the bug requires an application that calls\nASN1_mbstring_copy() or ASN1_mbstring_ncopy() directly, or registers\na custom string type via ASN1_STRING_TABLE_add(), with\nattacker-controlled input on the order of half a gigabyte or more.\nFor these reasons this issue was assigned Low severity.\n\nThe FIPS modules in 4.0, 3.6, 3.5, 3.4 and 3.0 are not affected by\nthis issue, as the affected code is outside the OpenSSL FIPS module\nboundary.(CVE-2026-7383)",
  "id": "OESA-2026-2750",
  "modified": "2026-08-06T11:11:40Z",
  "published": "2026-06-24T11:11:40Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2750"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34180"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45447"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-7383"
    }
  ],
  "schema_version": "1.7.2",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "shim security update",
  "upstream": [
    "CVE-2026-34180",
    "CVE-2026-45447",
    "CVE-2026-7383"
  ]
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.



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.