{"id":"CVE-2026-55737","state":"PUBLISHED","title":"Heap pointer corruption via signed/unsigned mismatch in LARGE_TUPLE_EXT decoding in erts external term format decoder","description":"Signed to Unsigned Conversion Error and Out-of-bounds Write vulnerability in Erlang OTP erts allows an attacker who can supply a crafted Erlang external term format (ETF) binary to binary_to_term/1 to corrupt the BEAM heap pointer and crash the virtual machine.\n\nWhen decoding a LARGE_TUPLE_EXT term, the validation pass decoded_size() in erts/emulator/beam/external.c reads the 32-bit arity field as unsigned (get_uint32()), while the decode pass dec_term() reads the same field as a signed 32-bit integer (get_int32()) into an int. An arity wire value of 0x80000000 passes validation as 2147483648 but decodes as -2147483648, so the subsequent hp += n moves the heap allocation pointer backward. Neither pass enforces the runtime tuple-arity limit MAX_ARITYVAL. The result is an out-of-bounds heap write; in practice the VM detects an impossible heap size and aborts, denying service. The required padding is large when uncompressed but the compressed-ETF envelope shrinks it to a small payload on the wire.\n\nThis issue affects OTP from OTP 25.0 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15, corresponding to erts from 13.0 before 17.0.4, 16.4.0.4 and 15.2.7.11.","publishedAt":"2026-07-27T15:13:54.699Z","updatedAt":"2026-07-28T09:55:26.434Z","severity":{"score":5.1,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","source":"EEF"},"assigner":"EEF","products":["Erlang OTP"],"affected":[{"vendor":"Erlang","product":"OTP","packageName":"erts","packageURL":"pkg:otp/erts?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%20https:%2F%2Fgithub.com%2Ferlang%2Fotp.git","defaultStatus":"unaffected","versions":[{"version":"13.0","status":"affected","lessThan":"*","changes":[{"at":"17.0.4","status":"unaffected"},{"at":"16.4.0.4","status":"unaffected"},{"at":"15.2.7.11","status":"unaffected"}],"versionType":"otp"}],"cpes":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"modules":["erlang","external"],"programFiles":["emulator/beam/external.c"],"programRoutines":[{"name":"erlang:binary_to_term/1"},{"name":"erlang:binary_to_term/2"},{"name":"dec_term"},{"name":"decoded_size"}],"repo":"https://github.com/erlang/otp"},{"vendor":"Erlang","product":"OTP","packageName":"erlang/otp","packageURL":"pkg:github/erlang/otp","defaultStatus":"unaffected","versions":[{"version":"25.0","status":"affected","lessThan":"*","changes":[{"at":"29.0.4","status":"unaffected"},{"at":"28.5.0.4","status":"unaffected"},{"at":"27.3.4.15","status":"unaffected"}],"versionType":"otp"},{"version":"ebcbb97b4ec223464cac3d94375739a248ddef6e","status":"affected","lessThan":"c5210b42a9d3d96f3d25601942ce8122be0f3761","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"modules":["erlang","external"],"programFiles":["erts/emulator/beam/external.c"],"programRoutines":[{"name":"erlang:binary_to_term/1"},{"name":"erlang:binary_to_term/2"},{"name":"dec_term"},{"name":"decoded_size"}],"repo":"https://github.com/erlang/otp"}],"references":["https://github.com/erlang/otp/security/advisories/GHSA-446w-268v-9462","https://cna.erlef.org/cves/CVE-2026-55737.html","https://osv.dev/vulnerability/EEF-CVE-2026-55737","https://www.erlang.org/doc/system/versions.html#order-of-versions","https://github.com/erlang/otp/commit/c5210b42a9d3d96f3d25601942ce8122be0f3761"],"weaknesses":["CWE-195","CWE-787"],"ingestedAt":"2026-10-29T20:12:24.861Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/55xxx/CVE-2026-55737.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-55737","state":"PUBLISHED","datePublished":"2026-07-27T15:13:54.699Z","dateUpdated":"2026-07-28T09:55:26.434Z","assignerShortName":"EEF","assignerOrgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateReserved":"2026-06-17T10:44:34.365Z"},"containers":{"cna":{"title":"Heap pointer corruption via signed/unsigned mismatch in LARGE_TUPLE_EXT decoding in erts external term format decoder","descriptions":[{"lang":"en","value":"Signed to Unsigned Conversion Error and Out-of-bounds Write vulnerability in Erlang OTP erts allows an attacker who can supply a crafted Erlang external term format (ETF) binary to binary_to_term/1 to corrupt the BEAM heap pointer and crash the virtual machine.\n\nWhen decoding a LARGE_TUPLE_EXT term, the validation pass decoded_size() in erts/emulator/beam/external.c reads the 32-bit arity field as unsigned (get_uint32()), while the decode pass dec_term() reads the same field as a signed 32-bit integer (get_int32()) into an int. An arity wire value of 0x80000000 passes validation as 2147483648 but decodes as -2147483648, so the subsequent hp += n moves the heap allocation pointer backward. Neither pass enforces the runtime tuple-arity limit MAX_ARITYVAL. The result is an out-of-bounds heap write; in practice the VM detects an impossible heap size and aborts, denying service. The required padding is large when uncompressed but the compressed-ETF envelope shrinks it to a small payload on the wire.\n\nThis issue affects OTP from OTP 25.0 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15, corresponding to erts from 13.0 before 17.0.4, 16.4.0.4 and 15.2.7.11."}],"affected":[{"vendor":"Erlang","product":"OTP","packageName":"erts","packageURL":"pkg:otp/erts?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%20https:%2F%2Fgithub.com%2Ferlang%2Fotp.git","defaultStatus":"unaffected","versions":[{"version":"13.0","status":"affected","lessThan":"*","changes":[{"at":"17.0.4","status":"unaffected"},{"at":"16.4.0.4","status":"unaffected"},{"at":"15.2.7.11","status":"unaffected"}],"versionType":"otp"}],"cpes":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"modules":["erlang","external"],"programFiles":["emulator/beam/external.c"],"programRoutines":[{"name":"erlang:binary_to_term/1"},{"name":"erlang:binary_to_term/2"},{"name":"dec_term"},{"name":"decoded_size"}],"repo":"https://github.com/erlang/otp"},{"vendor":"Erlang","product":"OTP","packageName":"erlang/otp","packageURL":"pkg:github/erlang/otp","defaultStatus":"unaffected","versions":[{"version":"25.0","status":"affected","lessThan":"*","changes":[{"at":"29.0.4","status":"unaffected"},{"at":"28.5.0.4","status":"unaffected"},{"at":"27.3.4.15","status":"unaffected"}],"versionType":"otp"},{"version":"ebcbb97b4ec223464cac3d94375739a248ddef6e","status":"affected","lessThan":"c5210b42a9d3d96f3d25601942ce8122be0f3761","versionType":"git"}],"collectionURL":"https://github.com","cpes":["cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"],"modules":["erlang","external"],"programFiles":["erts/emulator/beam/external.c"],"programRoutines":[{"name":"erlang:binary_to_term/1"},{"name":"erlang:binary_to_term/2"},{"name":"dec_term"},{"name":"decoded_size"}],"repo":"https://github.com/erlang/otp"}],"references":[{"url":"https://github.com/erlang/otp/security/advisories/GHSA-446w-268v-9462","tags":["vendor-advisory","related"]},{"url":"https://cna.erlef.org/cves/CVE-2026-55737.html","tags":["related"]},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-55737","tags":["related"]},{"url":"https://www.erlang.org/doc/system/versions.html#order-of-versions","tags":["x_version-scheme"]},{"url":"https://github.com/erlang/otp/commit/c5210b42a9d3d96f3d25601942ce8122be0f3761","tags":["patch"]}],"metrics":[{"cvssV4_0":{"attackComplexity":"LOW","attackRequirements":"NONE","attackVector":"LOCAL","baseScore":5.1,"baseSeverity":"MEDIUM","privilegesRequired":"NONE","subAvailabilityImpact":"NONE","subConfidentialityImpact":"NONE","subIntegrityImpact":"NONE","userInteraction":"NONE","vectorString":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","version":"4.0","vulnAvailabilityImpact":"LOW","vulnConfidentialityImpact":"NONE","vulnIntegrityImpact":"NONE"},"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}]}],"problemTypes":[{"descriptions":[{"cweId":"CWE-195","description":"CWE-195 Signed to Unsigned Conversion Error","lang":"en","type":"CWE"},{"cweId":"CWE-787","description":"CWE-787 Out-of-bounds Write","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"EEF","orgId":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db","dateUpdated":"2026-07-28T09:55:26.434Z"},"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*","versionEndExcluding":"27.3.4.15","versionStartIncluding":"25.0","vulnerable":true},{"criteria":"cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*","versionEndExcluding":"28.5.0.4","versionStartIncluding":"28.0","vulnerable":true},{"criteria":"cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*","versionEndExcluding":"29.0.4","versionStartIncluding":"29.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"AND"}],"credits":[{"lang":"en","type":"finder","value":"Nick Gunn"},{"lang":"en","type":"remediation developer","value":"Kiko Fernandez-Reyes"},{"lang":"en","type":"remediation reviewer","value":"Sverker Eriksson"}],"impacts":[{"capecId":"CAPEC-92","descriptions":[{"lang":"en","value":"CAPEC-92 Forced Integer Overflow"}]}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"cvelib 1.8.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-07-27T18:34:45.698069Z","id":"CVE-2026-55737","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-07-27T18:34:55.080Z"}}]}}}