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Fencer Vulns
high 7.5

CVE-2020-15694 json

In Nim 1.2.4, the standard library httpClient fails to properly validate the server response.

published 2020-08-14 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-7681

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.3%
EPSS 2.3% chance of exploitation in 30 days, percentile 83%
public exploits
0
none known

Summary

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.

Patch / fix

  • nim Debian 14, Debian 12 1.2.6-1

debian advisories DEBIAN-CVE-2020-15694

  • nim openSUSE Tumbleweed 1.6.6-3.1
  • nim Package Hub 15 SP4, openSUSE Leap 15.4 1.6.6-bp154.2.3.1
  • nim Package Hub 15 SP3, openSUSE Leap 15.3 1.6.6-bp153.2.3.1

opensuse advisories openSUSE-SU-2024:12253-1openSUSE-SU-2022:10101-1openSUSE-SU-2022:10095-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-15694 updated cvss 7.5

nim: standard library httpClient fails to properly validate the server response

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.33% chance of exploitation in the next 30 days, higher than 83% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • openwall.com http://www.openwall.com/lists/oss-security/2021/02/04/2 referenced PoC, tagged "exploit" by a source, unverified
  • consensys.net https://consensys.net/diligence/vulnerabilities/nim-httpclient-header-crlf-injection/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:P/A:N

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.