Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.
AV AC PR UI S C I A CVSS EPSS %ile KEV N H N R U N L H 5.9 .4074 98.6 —
AFFECTED Product Versions Fixed python/cpython unspecified —
TIMELINE Jan 8 Reserved by snyk Feb 15 Published (CNA: snyk) Oct 14 EXPLOIT PUBLISHED — CVE-2021-23336 (python/cpython). Public exploit reference added.
The package python/cpython from 0 and before 3.6.13, from 3.7.0 and before 3.7.10, from 3.8.0 and before 3.8.8, from 3.9.0 and before 3.9.2 are vulnerable to Web Cache Poisoning via urllib.parse.parse_qsl and urllib.parse.parse_qs by using a vector called parameter cloaking. When the attacker can separate query parameters using a semicolon (;), they can cause a difference in the interpretation of the request between the proxy (running with default configuration) and the server. This can result in malicious requests being cached as completely safe ones, as the proxy would usually not see the semicolon as a separator, and therefore would not include it in a cache key of an unkeyed parameter.
| Date | Event | Detail |
|---|---|---|
| January 8, 2021 | Reserved | Reserved by snyk |
| February 15, 2021 | Published | Published (CNA: snyk) |
| October 14, 2026 | EXPLOIT PUBLISHED | EXPLOIT PUBLISHED — CVE-2021-23336 (python/cpython). Public exploit reference added. |
| Vendor | Product / Package | Ecosystem | Version introduced | Fixed |
|---|---|---|---|---|
| n/a | python/cpython | — | — | — |
Authoritative record: CVE-2021-23336 at cve.org
Weaknesses: CWE-444
This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2021-23336 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Monday, October 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.
