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CVE-2026-59250VulnerabilityPublished Updated

CVE-2026-59250: Erlang OTP · Classic Buffer Overflow

Affects Erlang OTPSource CVE Database V5

0

Not known to be exploited · CVSS 8.3 High · fixed in 29.0.4 : patch Erlang OTP soon.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score
8.3High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.7% chance of exploitation in 30 days – higher than 55% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 29.0.4, 28.5.0.4, 27.3.4.15 +4
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 2026-10-25.

What to do

Upgrade OTP to 29.0.4, 28.5.0.4 or 27.3.4.15; OTP and megaco to 4.9.1, 4.8.3.1 or 4.7.2.2; OTP to 8704c8f550a11ed5f825e3c011ecb03565b79c4f.

Affected software

ProductAffectedFixed in
ErlangOTPAffected
  • >=17.0 <27.3.4.15
  • >=28.0 <28.5.0.4
  • >=29.0 <29.0.4
Fixed in
  • 29.0.4
  • 28.5.0.4
  • 27.3.4.15
ErlangOTPAffected
  • >=3.17.1 <4.7.2.2
  • >=4.8 <4.8.3.1
  • >=4.9 <4.9.1
Fixed in
  • 4.9.1
  • 4.8.3.1
  • 4.7.2.2
ErlangOTPAffected
  • ≥ 84adefa331c4159d432d22840663c38f155cd4c1, < 8704c8f550a11ed5f825e3c011ecb03565b79c4f
Fixed in
  • 8704c8f550a11ed5f825e3c011ecb03565b79c4f
GitHubmegacopkg:github/megacoOther threatsAffected
  • >=3.17.1 <4.7.2.2
  • >=4.8 <4.8.3.1
  • >=4.9 <4.9.1
Fixed in
  • 4.7.2.2
  • 4.8.3.1
  • 4.9.1
GitHuberlang/otppkg:github/erlang/otpOther threatsAffected–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

If you cannot patch yet, restrict network access to the megaco transport port on nodes configured with {scanner, flex} to trusted sources only.

Description

Classic buffer overflow in the Erlang/OTP megaco flex scanner C driver allows a remote unauthenticated attacker to corrupt the driver's memory (and potentially achieve remote code execution or a denial-of-service crash) by sending a single text-encoded H.248/Megaco message containing an oversized property parm name. When tokenizing a Local/Remote descriptor, mfs_load_property_groups extracts the attacker-controlled property name (bounded only by the message length) and, when no value follows, formats it into a fixed 512-byte error_msg field of the MfsErlDrvData struct using an unchecked sprintf call. Names longer than roughly 452 bytes overflow into the immediately following struct fields (text_buf, text_ptr, term_spec, term_spec_size, term_spec_index), overwriting live pointers and counters with attacker-chosen bytes. Subsequent scanner code writes and frees through the corrupted pointers, producing arbitrary write and arbitrary free primitives inside the BEAM VM process, which can be leveraged for remote code execution. On builds compiled with _FORTIFY_SOURCE the overflow is detected at runtime and terminates the process with SIGABRT, resulting in denial of service. The overflow occurs in the flex scanner before any grammar or Megaco-level authentication processing, so exploitation requires only network reachability to the megaco transport port on a node configured with {scanner, flex}. This vulnerability is associated with program files lib/megaco/src/flex/megaco_flex_scanner_drv.flex.src and program routines mfs_load_property_groups. This issue affects OTP from OTP 17.0 before OTP 27.3.4.15, from OTP 28.0 before OTP 28.5.0.4, and from OTP 29.0 before OTP 29.0.4, corresponding to megaco from 3.17.1 before 4.7.2.2, from 4.8 before 4.8.3.1, and from 4.9 before 4.9.1. Whether OTP before OTP 17.0, corresponding to megaco before 3.17.1, is affected is unknown.

References

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