CVE-2004-1464
CVE-2004-1464 is a security flaw in Cisco IOS, the operating system on Cisco’s routers and switches. Attackers can crash Cisco IOS or stop it working. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 19 May 2023.[1]
Cisco IOS 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. Cisco has published a fix or advice.
Description
CISA calls it a denial-of-service in Cisco IOS. In its words: “Cisco IOS contains an unspecified vulnerability that may block further telnet, reverse telnet, Remote Shell (RSH), Secure Shell (SSH), and in some cases, Hypertext Transport Protocol (HTTP) access to the Cisco device.”[1]
The underlying weakness is resource exhaustion (CWE-400), in MITRE’s list of common software weaknesses.[2]
It scores 5.9 out of 10 on the Common Vulnerability Scoring System, which rates it medium, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record doesn’t list version ranges for it; Cisco’s advisory has them[3]. CISA names the product as Cisco IOS.
Most families won’t have Cisco IOS; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 19 May 2023, 6,713 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 9 Jun 2023 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 5%. That’s in the top 8% of the flaws it scores.[4]
CISA assesses it as not automatable: each attack takes some work.
CISA doesn’t say who was attacked, or how.
Fix
Cisco has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.Cisco IOS 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 9 Jun 2023 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 5.9.[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 5%.[4] |
See also
Other Cisco IOS flaws
- CVE-2008-4128: cross-site request forgery ·
Other Cisco flaws
- CVE-2026-76418, Cisco Secure Firewall ASA Software and Cisco Secure FTD Software: unchecked return value to NULL pointer dereference ·
- CVE-2026-76519, Cisco Secure Email Gateway: relative path traversal ·
- CVE-2026-76504, Cisco Catalyst SD-WAN Manager: hex encoding ·
- CVE-2026-76460, Cisco Identity Services Engine: incorrect use of privileged APIs ·
- CVE-2026-76461, Cisco Secure Email Gateway: SQL injection ·
Other resource exhaustion flaws
- CVE-2026-28318, SolarWinds Serv-U: uncontrolled resource consumption ·
- CVE-2026-45498, Microsoft Defender: denial of service ·
- CVE-2023-44487, IETF HTTP/2: rapid reset attack ·
- CVE-2023-38180, Microsoft .NET Core and Visual Studio: denial-of-service ·
Added the same day
- CVE-2023-21492, Samsung Mobile Devices: insertion of sensitive information into log file ·
- CVE-2016-6415, Cisco IOS, IOS XR, and IOS XE: iKEv1 information disclosure ·
Every Cisco flaw on CISA’s list · Everything added in May 2023
References
- ^ Cybersecurity and Infrastructure Security Agency. “Cisco IOS Denial-of-Service Vulnerability”. Known Exploited Vulnerabilities Catalog, added 19 May 2023.
- ^ National Institute of Standards and Technology. “CVE-2004-1464 Detail”. National Vulnerability Database, published 31 Dec 2004.
- ^ Cisco. Advisories and fixes: sec.cloudapps.cisco.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.048, percentile 92.0, 31 Oct 2026.
- CVE Program. “CVE-2004-1464”. 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.