Description
In Nim 1.2.4, the standard library httpClient fails to properly validate the server response. For example, httpClient.get().contentLength() does not raise any error if a malicious server provides a negative Content-Length.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | nim | 1.2.6-1 | — |
| Debian 12 | nim | 1.2.6-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | nim | No fix yet | — |
| Ubuntu 18.04 LTS | nim | No fix yet | — |
| Ubuntu 16.04 LTS | nim | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE Package Hub 15 SP4 | nim | 1.6.6-bp154.2.3.1 | openSUSE-SU-2022:10101-1 |
| SUSE Package Hub 15 SP3 | nim | 1.6.6-bp153.2.3.1 | openSUSE-SU-2022:10095-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | nim | 1.6.6-3.1 | openSUSE-SU-2024:12253-1 |
| openSUSE Leap 15.4 | nim | 1.6.6-bp154.2.3.1 | openSUSE-SU-2022:10101-1 |
| openSUSE Leap 15.3 | nim | 1.6.6-bp153.2.3.1 | openSUSE-SU-2022:10095-1 |
Advisories 3
- openSUSE-SU-2022:10101-1 Security update for nim SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2022:10095-1 Security update for nim SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:12253-1 nim-1.6.6-3.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- https://github.com/nim-lang/Nim/blob/dc5a40f3f39c6ea672e6dc6aca7f8118a69dda99/lib/pure/httpclient.nim#L241
- https://nim-lang.org/blog/2020/07/30/versions-126-and-108-released.html
- [oss-security] 20210204 [CVE-2020-15693, CVE-2020-15694] Nim - stdlib Httpclient - Header Crlf Injection & Server Response Validation mailing-list
- https://consensys.net/diligence/vulnerabilities/nim-httpclient-header-crlf-injection/