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Fencer Intel
medium 6.5

CVE-2026-77281 json

Caddy: rewrite placeholder re-expansion

published last mo. modified last mo. also CVE-2026-92284 , CVE-2026-92700 , EUVD-2026-82474 , GHSA-j8px-rmrx-76h9 , GO-2026-6512

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/caddyserver/caddy/v2 2.11.4
  • caddyserver caddy 2.11.4
  • caddy Debian 12 2.6.2-5+deb12u1
  • caddy Debian 14 2.11.4-1

debian advisories DEBIAN-CVE-2026-77281

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CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
last mo.

Exploit prediction

0.49% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

Affected packages

ecosystem package affected fixed in
go github.com/caddyserver/caddy/v2
<2.11.4
2.11.4

Affected products

  • caddyserver caddy

Classification

Weakness
  • CWE-94 Improper Control of Generation of Code
  • CWE-178 Improper Handling of Case Sensitivity
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Intel 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.