CVE-2017-17562
CVE-2017-17562 is a security flaw in Embedthis GoAhead. Attackers can run their own code on Embedthis GoAhead. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 10 Dec 2021.[1]
Embedthis GoAhead is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff.
Description
CISA calls it a remote code execution in Embedthis GoAhead. In its words: “Embedthis GoAhead before 3.6.5 allows remote code execution if CGI is enabled and a CGI program is dynamically linked.”[1]
The CVE record adds: “Embedthis GoAhead before 3.6.5 allows remote code execution if CGI is enabled and a CGI program is dynamically linked. This is a result of initializing the environment of forked CGI scripts using untrusted HTTP request parameters in the cgiHandler function in cgi.c. When combined with the glibc dynamic linker, this behaviour can be abused for remote code execution using special parameter names such as LD_PRELOAD. An attacker can POST their shared object payload in the body of the request, and reference it using /proc/self/fd/0.”[2]
The underlying weakness is improper input validation (CWE-20), in MITRE’s list of common software weaknesses.
It scores 8.1 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it. CISA names the product as Embedthis GoAhead.
Most families won’t have Embedthis GoAhead; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 10 Dec 2021, 1,459 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 10 Jun 2022 to fix it.[1]
FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at 97%. That’s in the top 1% of the flaws it scores.[3]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.Embedthis GoAhead is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
- Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 10 Jun 2022 to fix it.
- If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.
You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.
Timeline
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 8.1.[2] | |
| CISA adds it to its catalog of flaws known to be used in attacks.[1] | |
| CISA’s deadline for US government agencies to fix it.[1] | |
| FIRST puts the odds of it being used in attacks in the next 30 days at 97%.[3] |
See also
Other improper input validation flaws
- CVE-2026-93952, Arista VeloCloud Orchestrator: improper input validation ·
- CVE-2019-1068, Microsoft SQL Server: remote code execution ·
- CVE-2026-12569, PTC Windchill and FlexPLM: improper input validation ·
- CVE-2026-34910, Ubiquiti UniFi OS: improper input validation ·
- CVE-2026-6973, Ivanti Endpoint Manager Mobile (EPMM): improper input validation ·
Added the same day
- CVE-2021-44515, Zoho Desktop Central: authentication bypass ·
- CVE-2021-44228, Apache Log4j2: remote code execution ·
- CVE-2021-44168, Fortinet FortiOS: arbitrary file download ·
- CVE-2021-35394, Realtek Jungle Software Development Kit (SDK): jungle SDK remote code execution ·
- CVE-2020-8816, Pi-hole AdminLTE: remote code execution ·
References
- ^ Cybersecurity and Infrastructure Security Agency. “Embedthis GoAhead Remote Code Execution Vulnerability”. Known Exploited Vulnerabilities Catalog, added 10 Dec 2021.
- ^ National Institute of Standards and Technology. “CVE-2017-17562 Detail”. National Vulnerability Database, published 12 Dec 2017.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.971, percentile 99.9, 31 Oct 2026.
- CVE Program. “CVE-2017-17562”. The official CVE record.
This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.