CVE-2026-77281

MEDIUM

6.5

CVSS v3

Description

Caddy is an extensible server platform that uses TLS by default. In version 2.11.3 and earlier, three configuration-dependent weaknesses affect the handler and placeholder layer. In modules/caddyhttp/rewrite/rewrite.go, Rewrite.Rewrite() can pass attacker-controlled replacement bytes through buildQueryString for a second placeholder expansion when a rewrite URI ends with a literal question mark, allowing injected environment or request-variable placeholders to disclose data and, when the file provider is registered, allowing injected file placeholders to disclose readable files. The issue is fixed in version 2.11.4.

CWE-94Code Injection CWE-178 CWE-770Allocation of Resources Without Limits or Throttling

How to fix

Remediation Available

caddyDebian

Fixed in:2.11.4-1CVE-2026-77281

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityNone

AvailabilityLow

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

Exploit Intelligence

0.49%probability of exploitation in 30 days

40thpercentile

Moderate risk: more likely to be exploited than 40% of all known CVEs.

References

Other references4

Related Vulnerabilities

Other CWE-94 (Code Injection) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2017-9841	Critical	9.8	100%	KEV	Fix
CVE-2015-1635	Critical	9.8	100%	KEV	-
CVE-2022-22954	Critical	9.8	100%	KEV + Ransom	-
CVE-2025-49704	High	8.8	100%	KEV + Ransom	Fix
CVE-2025-3248	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2021-22204	Medium	6.8	100%	KEV	Fix

Common questions

How do I fix CVE-2026-77281?

Upgrade caddy on debian unstable to 2.11.4-1 or later.

Is CVE-2026-77281 being actively exploited?

Not that we know of. CVE-2026-77281 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.49% is the estimated probability that it will be exploited in the next 30 days. That is higher than 40% of all scored CVEs.

How severe is CVE-2026-77281?

CVE-2026-77281 has a CVSS v3 base score of 6.5, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2026-77281 affect?

Published advisories record a fix for caddy (Debian). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

Embed a live status badge for CVE-2026-77281

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-09-24.