Skip to content
Heist/ feed
Back to feed
High

wabt — security advisory

Type: advisorySources: OSVAdvisory ID: UBUNTU-CVE-2026-90648

wasm2c in WebAssembly wabt through 1.0.41 allows sandbox escape in some situations that primarily involve 32-bit platforms, aka a "table flip" attack. It does not check the return value of calloc() in wasm_rt_allocate_funcref_table() (wasm2c/wasm-rt-impl-tableops.inc). When the funcref table allocation fails, table->data is left NULL while table->size keeps the guest-declared element count; thus, bounds checks still pass and table element accesses resolve to absolute memory addresses (i * sizeof(wasm_rt_funcref_t)). This gives arbitrary read and write of host process memory and - via table.get, table.set, and call_indirect - arbitrary code execution, defeating the isolation that wasm2c exists to provide (a full sandbox escape). wasm2c is used as an in-process sandboxing boundary by RLBox and WasmBoxC, including in Firefox, which compiles the Graphite, Hunspell, Ogg, Expat, and Woff2 libraries via wasm2c to contain untrusted font, media, and XML input. Therefore, sandboxing in these applications is potentially affected. Exploitation requires the funcref table allocation to fail, for example under an address-space limit (RLIMIT_AS), on 32-bit hosts, with vm.overcommit_memory=2, or under memory pressure. On 64-bit Linux with default overcommit the allocation succeeds and the defect is not triggered. The wasm2c memory allocator aborts on calloc failure in the same runtime; the table allocator lacks this abort behavior. This was introduced in commit ab9e0b55 (PR #813).

Products
wabt
Affected versions
1.0.11-1, 1.0.12-1, 1.0.13-1, 1.0.13-1build1, 1.0.20-1, 1.0.24-1, 1.0.24-2, 1.0.25-1, 1.0.26-1, 1.0.27-1, 1.0.33-1, 1.0.34+dsfg2+~cs1.0.32-1ubuntu1, 1.0.34+dsfg2+~cs1.0.32-1ubuntu2, 1.0.34-1, 1.0.36+dfsg+~cs1.0.36-2ubuntu1, 1.0.36+dfsg+~cs1.0.36-2ubuntu4
Fixed versions
Not specified
CVEs
CVE-2026-90648
Confirmed fixed CVEs
Not specified
Updated in this feed
31 Oct 2026, 03:31 UTC · Revision 1

Source evidence

UBUNTU-CVE-2026-90648

core-osv · Original source

Published 13 Sept 2026, 00:17 UTC

wasm2c in WebAssembly wabt through 1.0.41 allows sandbox escape in some situations that primarily involve 32-bit platforms, aka a "table flip" attack. It does not check the return value of calloc() in wasm_rt_allocate_funcref_table() (wasm2c/wasm-rt-impl-tableops.inc). When the funcref table allocation fails, table->data is left NULL while table->size keeps the guest-declared element count; thus, bounds checks still pass and table element accesses resolve to absolute memory addresses (i * sizeof(wasm_rt_funcref_t)). This gives arbitrary read and write of host process memory and - via table.get, table.set, and call_indirect - arbitrary code execution, defeating the isolation that wasm2c exists to provide (a full sandbox escape). wasm2c is used as an in-process sandboxing boundary by RLBox and WasmBoxC, including in Firefox, which compiles the Graphite, Hunspell, Ogg, Expat, and Woff2 libraries via wasm2c to contain untrusted font, media, and XML input. Therefore, sandboxing in these applications is potentially affected. Exploitation requires the funcref table allocation to fail, for example under an address-space limit (RLIMIT_AS), on 32-bit hosts, with vm.overcommit_memory=2, or under memory pressure. On 64-bit Linux with default overcommit the allocation succeeds and the defect is not triggered. The wasm2c memory allocator aborts on calloc failure in the same runtime; the table allocator lacks this abort behavior. This was introduced in commit ab9e0b55 (PR #813).

osv:UBUNTU-CVE-2026-90648

wabt

Fixed versions: Not specified

wabt

Fixed versions: Not specified

wabt

Fixed versions: Not specified

wabt

Fixed versions: Not specified

wabt

Fixed versions: Not specified

Complete source record
{
  "id": "fd8860da65f9212b76d416047ab62673cc5b21b3e5b84ab73b04f202805eeb24",
  "url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-90648",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "UBUNTU-CVE-2026-90648",
    "summary": "wasm2c in WebAssembly wabt through 1.0.41 allows sandbox escape in some situations that primarily involve 32-bit platforms, aka a \"table flip\" attack. It does not check the return value of calloc() in wasm_rt_allocate_funcref_table() (wasm2c/wasm-rt-impl-tableops.inc). When the funcref table allocation fails, table->data is left NULL while table->size keeps the guest-declared element count; thus, bounds checks still pass and table element accesses resolve to absolute memory addresses (i * sizeof(wasm_rt_funcref_t)). This gives arbitrary read and write of host process memory and - via table.get, table.set, and call_indirect - arbitrary code execution, defeating the isolation that wasm2c exists to provide (a full sandbox escape). wasm2c is used as an in-process sandboxing boundary by RLBox and WasmBoxC, including in Firefox, which compiles the Graphite, Hunspell, Ogg, Expat, and Woff2 libraries via wasm2c to contain untrusted font, media, and XML input. Therefore, sandboxing in these applications is potentially affected. Exploitation requires the funcref table allocation to fail, for example under an address-space limit (RLIMIT_AS), on 32-bit hosts, with vm.overcommit_memory=2, or under memory pressure. On 64-bit Linux with default overcommit the allocation succeeds and the defect is not triggered. The wasm2c memory allocator aborts on calloc failure in the same runtime; the table allocator lacks this abort behavior. This was introduced in commit ab9e0b55 (PR #813).",
    "evidence": "osv:UBUNTU-CVE-2026-90648",
    "products": [
      {
        "name": {
          "value": "wabt",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.0.11-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.0.12-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.0.13-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "1.0.13-1build1",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "wabt",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.0.20-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.0.24-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.0.24-2",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.0.25-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.0.26-1",
            "evidence": "/affected/1/versions"
          },
          {
            "value": "1.0.27-1",
            "evidence": "/affected/1/versions"
          }
        ]
      },
      {
        "name": {
          "value": "wabt",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.0.33-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.0.34-1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.0.34+dsfg2+~cs1.0.32-1ubuntu1",
            "evidence": "/affected/2/versions"
          },
          {
            "value": "1.0.34+dsfg2+~cs1.0.32-1ubuntu2",
            "evidence": "/affected/2/versions"
          }
        ]
      },
      {
        "name": {
          "value": "wabt",
          "evidence": "/affected/3/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.0.36+dfsg+~cs1.0.36-2ubuntu1",
            "evidence": "/affected/3/versions"
          },
          {
            "value": "1.0.36+dfsg+~cs1.0.36-2ubuntu4",
            "evidence": "/affected/3/versions"
          }
        ]
      },
      {
        "name": {
          "value": "wabt",
          "evidence": "/affected/4/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": [
          {
            "value": "1.0.36+dfsg+~cs1.0.36-2ubuntu1",
            "evidence": "/affected/4/versions"
          }
        ]
      }
    ],
    "severity": "high",
    "structured": {
      "id": "UBUNTU-CVE-2026-90648",
      "aliases": [
        "UBUNTU-CVE-2026-90648"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:H"
        },
        {
          "type": "Ubuntu",
          "score": "medium"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "wabt",
            "purl": "pkg:deb/ubuntu/wabt?arch=source&distro=focal",
            "ecosystem": "Ubuntu:20.04:LTS"
          },
          "versions": [
            "1.0.11-1",
            "1.0.12-1",
            "1.0.13-1",
            "1.0.13-1build1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-90648.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "wabt",
                "binary_version": "1.0.13-1build1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "wabt",
            "purl": "pkg:deb/ubuntu/wabt?arch=source&distro=jammy",
            "ecosystem": "Ubuntu:22.04:LTS"
          },
          "versions": [
            "1.0.20-1",
            "1.0.24-1",
            "1.0.24-2",
            "1.0.25-1",
            "1.0.26-1",
            "1.0.27-1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-90648.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "wabt",
                "binary_version": "1.0.27-1"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "wabt",
            "purl": "pkg:deb/ubuntu/wabt?arch=source&distro=noble",
            "ecosystem": "Ubuntu:24.04:LTS"
          },
          "versions": [
            "1.0.33-1",
            "1.0.34-1",
            "1.0.34+dsfg2+~cs1.0.32-1ubuntu1",
            "1.0.34+dsfg2+~cs1.0.32-1ubuntu2"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-90648.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "wabt",
                "binary_version": "1.0.34+dsfg2+~cs1.0.32-1ubuntu2"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "wabt",
            "purl": "pkg:deb/ubuntu/wabt?arch=source&distro=stonking",
            "ecosystem": "Ubuntu:26.10"
          },
          "versions": [
            "1.0.36+dfsg+~cs1.0.36-2ubuntu1",
            "1.0.36+dfsg+~cs1.0.36-2ubuntu4"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-90648.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "wabt",
                "binary_version": "1.0.36+dfsg+~cs1.0.36-2ubuntu4"
              }
            ]
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                }
              ]
            }
          ],
          "package": {
            "name": "wabt",
            "purl": "pkg:deb/ubuntu/wabt?arch=source&distro=resolute",
            "ecosystem": "Ubuntu:26.04:LTS"
          },
          "versions": [
            "1.0.36+dfsg+~cs1.0.36-2ubuntu1"
          ],
          "database_specific": {
            "source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-90648.json"
          },
          "ecosystem_specific": {
            "binaries": [
              {
                "binary_name": "wabt",
                "binary_version": "1.0.36+dfsg+~cs1.0.36-2ubuntu1"
              }
            ]
          }
        }
      ],
      "modified": "2026-10-17T13:01:16.424070838Z",
      "provider": "osv",
      "upstream": [
        "CVE-2026-90648"
      ],
      "references": [
        "https://ubuntu.com/security/CVE-2026-90648",
        "https://www.cve.org/CVERecord?id=CVE-2026-90648",
        "https://github.com/trustsig-eu/wasm2c-tableflip",
        "https://bugzilla.mozilla.org/show_bug.cgi?id=1827704",
        "https://github.com/WebAssembly/wabt",
        "https://https://blog.mozilla.org/attack-and-defense/2021/12/06/webassembly-and-back-again-fine-grained-sandboxing-in-firefox-95",
        "https://rlbox.dev"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2026-90648",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 361450,
  "published_at": "2026-09-13T00:17:00+00:00"
}