Gogs: Open Redirect in /redirect endpoint via backslash bypass in `IsSameSite`

published 2026-10-14 25 d ago modified 2026-10-20 20 d ago also EUVD-2026-101576

cvss: 5.3; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 38%
public exploits: 0; none known

Gogs is an open source self-hosted Git service. Prior to 0.15.0+dev, an unauthenticated attacker can provide a backslash-containing target to the /redirect endpoint, and similar post-action redirect flows are also affected. internal/urlx/urlx.go IsSameSite validates a normalized form of the target while cmd/gogs/internal/web/web.go getRedirect and other callers use the original value in the Location response. This backslash normalization mismatch lets browsers interpret the Location value as a scheme-relative external URL, allowing links on a trusted Gogs domain to redirect victims to attacker-controlled content for phishing. This vulnerability is fixed in 0.15.0+dev.

Patch / fix

fixed in 1 links 2

gogs gogs 0.15.0+dev

github.com/gogs/gogs@0aa820e commit
github.com/gogs/gogs#8391 pull request

CISA SSVC

Exploitation: Proof of concept is public
Automatable: no
Technical impact: partial
Assessed: 20 d ago (2026-10-20)

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

github.com https://github.com/gogs/gogs/security/advisories/GHSA-3g28-2vwg-gxq6 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	4.0	5.3	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N
CNA	4.0	5.3	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

gogs gogs

Classification

Weakness

CWE-601 URL Redirection to Untrusted Site

References

Sources

CVE List CVE-2026-82402
NVD CVE-2026-82402

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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.

Summary