Public proof of conceptFix available

CVE-2021-25980

A public proof of concept exists; no exploitation attested.

Published2021-11-11
WeaknessCWE-74

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

In Talkyard, versions v0.04.01 through v0.6.74-WIP-63220cb, v0.2020.22-WIP-b2e97fe0e through v0.2021.02-WIP-879ef3fe1 and tyse-v0.2021.02-879ef3fe1-regular through tyse-v0.2021.28-af66b6905-regular, are vulnerable to Host Header Injection. By luring a victim application-user to click on a link, an unauthenticated attacker can use the “forgot password” functionality to reset the victim’s password and successfully take over their account.

Timeline

dates in UTC

2021-11-1107:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-25980?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-25980?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD

Talkyard

Branch	Affected	Fixed in	Source
0.x	≥ 0.04.01, ≤ 0.6.74-wip-63220cb	no fix published	NVD
0.x	≥ 0.2020.22-wip-b2e97fe0e, ≤ 0.2021.02-wip-879ef3fe1	no fix published	NVD
—	≥ tyse-v0.2021.02-879ef3fe1-regular, ≤ tyse-v0.2021.28-af66b6905-regular	no fix published	NVD

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

Advisories and patches

github.comPatch

Detection

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: none listed

Sources

CISA-ADPSSVC decisionpoc2025-04-30
OpenCVESSVC decisionpoc—
CNACVSS 3.18.8read 2026-10-23
NVDCVSS 3.18.8read 2026-10-23
NVDCVSS 2.06.8read 2026-10-23
CNAweakness (CWE)CWE-74read 2026-10-23
NVDweakness (CWE)CWE-74read 2026-10-23
FIRST EPSSEPSS score1.3 %2026-10-23

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Published: 2021-11-11
Last Modified: 2026-06-17
NVD status: Modified

Frequently asked questions

What is CVE-2021-25980?

Is CVE-2021-25980 actively exploited?

A proof-of-concept exploit exists for CVE-2021-25980, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2021-25980?

CVE-2021-25980 has a CVSS v3 base score of 8.8 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

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