CVE-2026-48164
Collabora Online: Reflected HTML injection through host_session_id
Collabora Online is a collaborative online office suite based on LibreOffice technology. Prior to 24.04.18 and 25.04.11, the host_session_id query/form parameter is substituted into the cool.html editor page without HTML encoding, unlike parameters passed through the existing variable-encoding mechanism. An attacker who induces a victim to load a crafted URL can inject HTML and, in the absence of an effective Content Security Policy, execute scripts in the Collabora Online iframe's origin, exposing the session authentication token and page contents. A reverse proxy that preserves the Content Security Policy header sent by coolwsd mitigates the script-execution scenario. This issue is fixed in versions 24.04.18 and 25.04.11.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Required
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
4.7
Collabora Online: Reflected HTML injection through host_session_id
Collabora Online is a collaborative online office suite based on LibreOffice technology. Prior to 24.04.18 and 25.04.11, the host_session_id query/form parameter is substituted into the cool.html editor page without HTML encoding, unlike parameters passed through the existing variable-encoding mechanism. An attacker who induces a victim to load a crafted URL can inject HTML and, in the absence of an effective Content Security Policy, execute scripts in the Collabora Online iframe's origin, exposing the session authentication token and page contents. A reverse proxy that preserves the Content Security Policy header sent by coolwsd mitigates the script-execution scenario. This issue is fixed in versions 24.04.18 and 25.04.11.
- Record
CVE-2026-48164- CVSS 3.1
- 4.7 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
EUVDEUVD-2026-114089
4.7
Collabora Online is a collaborative online office suite based on LibreOffice technology. Prior to 24.04.18 and 25.04.11, the host_session_id query/form parameter is substituted into the cool.html editor page without HTML encoding, unlike parameters passed through the existing variable-encoding mechanism. An attacker who induces a victim to load a crafted URL can inject HTML and, in the absence of an effective Content Security Policy, execute scripts in the Collabora Online iframe's origin, exposing the session authentication token and page contents. A reverse proxy that preserves the Content Security Policy header sent by coolwsd mitigates the script-execution scenario. This issue is fixed in versions 24.04.18 and 25.04.11.
- Record
EUVD-2026-114089- CVSS 3.1
- 4.7 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N - Updated
- 2026-11-02
NVD
4.7
Collabora Online is a collaborative online office suite based on LibreOffice technology. Prior to 24.04.18 and 25.04.11, the host_session_id query/form parameter is substituted into the cool.html editor page without HTML encoding, unlike parameters passed through the existing variable-encoding mechanism. An attacker who induces a victim to load a crafted URL can inject HTML and, in the absence of an effective Content Security Policy, execute scripts in the Collabora Online iframe's origin, exposing the session authentication token and page contents. A reverse proxy that preserves the Content Security Policy header sent by coolwsd mitigates the script-execution scenario. This issue is fixed in versions 24.04.18 and 25.04.11.
- Record
CVE-2026-48164- CVSS 3.1
- 4.7 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
OSV
4.7
Collabora Online: Reflected HTML injection through host_session_id
Collabora Online is a collaborative online office suite based on LibreOffice technology. Prior to 24.04.18 and 25.04.11, the host_session_id query/form parameter is substituted into the cool.html editor page without HTML encoding, unlike parameters passed through the existing variable-encoding mechanism. An attacker who induces a victim to load a crafted URL can inject HTML and, in the absence of an effective Content Security Policy, execute scripts in the Collabora Online iframe's origin, exposing the session authentication token and page contents. A reverse proxy that preserves the Content Security Policy header sent by coolwsd mitigates the script-execution scenario. This issue is fixed in versions 24.04.18 and 25.04.11.
- Record
CVE-2026-48164- CVSS 3.1
- 4.7 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N - Weakness
- CWE-79
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-48164 is a medium vulnerability (CVSS 4.7) in Collaboraonline Online, published October 30, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.33%, the 25th percentile. No source names a fixed version.