CVE-2026-55737: Erlang OTP · Signed to Unsigned Conversion Error
Affects Erlang OTPSource CVE Database V5
Not known to be exploited · CVSS 5.1 Medium : upgrade to c5210b42a9d3d96f3d25601942ce8122be0f3761 when convenient.
Data as of 26 Oct 2026, 10:12 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 21% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in c5210b42a9d3d96f3d25601942ce8122be0f3761, 17.0.4, 29.0.4
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 27 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade OTP to c5210b42a9d3d96f3d25601942ce8122be0f3761; erts to 17.0.4; erlang/otp to 29.0.4.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| ErlangOTP | Affected
| Fixed in– |
| ErlangOTP | Affected
| Fixed in
|
GitHubertspkg:github/ertsOther threats | Affected
| Fixed in
|
GitHuberlang/otppkg:github/erlang/otpOther threats | Affected
| Fixed in
|
CPE configurations (1)
cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Until then, avoid processing untrusted external term format binaries with binary_to_term/1.
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. When 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. This 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.
References
- github.com/erlang/otp/security/advisories/GHSA-446w-268v-9462 (opens in a new tab)
- cna.erlef.org/cves/CVE-2026-55737.html (opens in a new tab)
- osv.dev/vulnerability/EEF-CVE-2026-55737 (opens in a new tab)
- erlang.org/doc/system/versions.html (opens in a new tab)
- github.com/erlang/otp/commit/c5210b42a9d3d96f3d25601942ce8122be0f3761 (opens in a new tab)