CVE-2020-11899
CVE-2020-11899 is a security flaw in Treck TCP/IP stack IPv6. Attackers can corrupt memory in Treck TCP/IP stack IPv6, which they use to take it over. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 3 Mar 2022.[1]
Treck TCP/IP stack IPv6 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. Treck TCP/IP stack has published a fix or advice.
Description
CISA calls it an out-of-bounds read in Treck TCP/IP stack IPv6. In its words: “The Treck TCP/IP stack contains an IPv6 out-of-bounds read vulnerability.”[1]
The underlying weakness is out-of-bounds read (CWE-125), in MITRE’s list of common software weaknesses.[2]
It scores 5.4 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; Treck TCP/IP stack’s advisory has them[3]. CISA names the product as Treck TCP/IP stack IPv6.
Most families won’t have Treck TCP/IP stack IPv6; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 3 Mar 2022, 624 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 17 Mar 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 18%. That’s in the top 3% 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
Treck TCP/IP stack has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.Treck TCP/IP stack IPv6 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 17 Mar 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 5.4.[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 18%.[4] |
See also
Other out-of-bounds read flaws
- CVE-2023-36424, Microsoft Windows: out-of-bounds read ·
- CVE-2026-3055, Citrix NetScaler: out-of-bounds read ·
- CVE-2025-5777, Citrix NetScaler ADC and Gateway: out-of-bounds read ·
- CVE-2025-5419, Chrome and other Chromium browsers: out-of-bounds read and write ·
- CVE-2024-53150, Linux Kernel: out-of-bounds read ·
Added the same day
- CVE-2022-20708, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
- CVE-2022-20703, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
- CVE-2022-20701, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
- CVE-2022-20700, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
- CVE-2022-20699, Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers: small business RV series routers stack-based buffer overflow ·
References
- ^ Cybersecurity and Infrastructure Security Agency. “Treck TCP/IP stack Out-of-Bounds Read Vulnerability”. Known Exploited Vulnerabilities Catalog, added 3 Mar 2022.
- ^ National Institute of Standards and Technology. “CVE-2020-11899 Detail”. National Vulnerability Database, published 17 Jun 2020.
- ^ Treck TCP/IP stack. Advisories and fixes: kb.cert.org, treck.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.184, percentile 97.2, 31 Oct 2026.
- CVE Program. “CVE-2020-11899”. 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.