httpc does not bound server-supplied numeric header values before integer conversion
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · Low
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA.
Summary
Improper Validation of Specified Quantity in Input vulnerability in Erlang/OTP inets httpc allows a malicious or compromised HTTP server to degrade availability by returning a numeric header whose value is a very long run of digits. httpc_handler.erl converts the server-supplied Content-Length with list_to_integer/1 before comparing it against max_body_size, so the size check cannot protect the conversion, and the option defaults to nolimit in any case. The same unbounded conversion appears in httpc_response:format_response/1 for Content-Length and in httpc_response:get_ms_from_retry_after/1 for Retry-After, which is guarded only by a check that the first character is a digit. A value of up to roughly 1.26 million digits converts successfully and costs the requesting process hundreds of milliseconds of arbitrary-precision arithmetic per response. The conversion function is documented to accept integers of any size, so bounding the input is the caller's responsibility. This issue affects OTP from OTP 17.0 before OTP 27.3.4.17, from OTP 28.0 before OTP 28.5.0.6, and from OTP 29.0 before OTP 29.0.6, corresponding to inets from 5.10 before 9.3.2.7, from 9.4 before 9.6.2.3, and from 9.7 before 9.7.2. Whether OTP before OTP 17.0, corresponding to inets before 5.10, is affected is unknown.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Erlang | OTP | 17.0 to before 27.3.4.17; 28.0 to before 28.5.0.6; 29.0 to before 29.0.6 | 27.3.4.17, 28.5.0.6, 29.0.6 | Patch available | CNA |
| Erlang | OTP | 5.10 to before 9.3.2.7; 9.4 to before 9.6.2.3; 9.7 to before 9.7.2 | 9.3.2.7, 9.6.2.3, 9.7.2 | Patch available | CNA |
- OTP VendorErlang Affected 17.0 to before 27.3.4.17; 28.0 to before 28.5.0.6; 29.0 to before 29.0.6 Fixed in 27.3.4.17, 28.5.0.6, 29.0.6 Patch available CNA
- OTP VendorErlang Affected 5.10 to before 9.3.2.7; 9.4 to before 9.6.2.3; 9.7 to before 9.7.2 Fixed in 9.3.2.7, 9.6.2.3, 9.7.2 Patch available CNA
Remediation
- Fix · CNA OTP (Erlang) Fixed in 27.3.4.17, 28.5.0.6, 29.0.6
- Fix · CNA OTP (Erlang) Fixed in 9.3.2.7, 9.6.2.3, 9.7.2
Fixed in the same release
Records fixed by the same vendor advisory or release, as the CNA lists them.
- Release ·
Erlang OTP 17.0, 27.3.4.17 and 2 more versions
11 records Highest priority Priority MEDIUM 2 MEDIUM, 9 LOW
Other records, highest priority first
- TI-2026-50021 httpd applies no timeout while receiving a request body, parking a worker on a stalled clientPriority MEDIUM 45
- TI-2026-52570 inets,httpd: Memory Exhaustion via Unenforced max_body_size During Chunked Body ReceptionPriority MEDIUM 44
- TI-2026-47459 httpd mod_auth directory protection bypassed by a doubled slash in the request pathPriority LOW 38
- Release ·
Erlang OTP 5.10, 9.3.2.7 and 2 more versions
9 records Highest priority Priority MEDIUM 2 MEDIUM, 7 LOW
Other records, highest priority first
- TI-2026-50021 httpd applies no timeout while receiving a request body, parking a worker on a stalled clientPriority MEDIUM 45
- TI-2026-52570 inets,httpd: Memory Exhaustion via Unenforced max_body_size During Chunked Body ReceptionPriority MEDIUM 44
- TI-2026-47459 httpd mod_auth directory protection bypassed by a doubled slash in the request pathPriority LOW 38
Timeline
- 2026-10-02 Threatist record created from CVE-2026-71562
References
Patch 2
More Erlang vulnerabilities
- TI-2025-23504 Erlang/OTP SSH Vulnerable to Pre-Authentication RCE KEVCVSS 3.1CRITICAL 10.0
- TI-2026-48954 httpd parks a request worker indefinitely on a malformed chunk size sent after the headers CVSS 4.0HIGH 8.7
- TI-2023-26623 The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6… CVSS 3.1MEDIUM 5.9
- TI-2026-71037 Path traversal in rebar3 via unvalidated dependency app names CVSS 4.0HIGH 7.5
- TI-2024-36042 ssl fails to validate incorrect extened key usage CVSS 3.1MEDIUM 5.5
- TI-2020-10791 Rebar3 versions 3.0.0-beta.3 to 3.13.2 are vulnerable to OS command injection via URL… CVSS 3.1CRITICAL 9.8
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences