CVE-2026-26378: Cross Site Scripting vulnerability in Koha 25.11 and before allows a remote attacker to execute arbitrary code

Q: How do I fix CVE-2026-26378?

koha: upgrade to newer than 25.11.00. Exact commands for each OS are on this page.

Q: Is CVE-2026-26378 being exploited?

CVE-2026-26378 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-26378 affect?

CVE-2026-26378 affects koha. Severity is medium (CVSS 5.4). Cross Site Scripting vulnerability in Koha 25.11 and before allows a remote attacker to execute arbitrary code via file upload function in Invoice features

Q: How urgent is CVE-2026-26378?

Priority 30/100. Public exploit reference

Routine

MEDIUM 5.4UPGRADE

CVE-2026-26378 is a medium-severity flaw (CVSS 5.4) affecting koha. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cross Site Scripting vulnerability in Koha 25.11 and before allows a remote attacker to execute arbitrary code via file upload function in Invoice features

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.3% (top 77%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-06-03
Last modified	2026-07-22

Publisher (CNA): MITRE · Vendor: koha

Last updated 2026-07-22 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-03 19:16 UTCPublished CVE record published
2026-07-22 20:10 UTCUpdated Record last modified

koha koha UPGRADE

Affected: <= 25.11.00

Fixed in: newer than 25.11.00

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy koha || rpm -q koha || koha --version

2. UPGRADE to newer than 25.11.00 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade koha

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade koha

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-26378?

koha: upgrade to newer than 25.11.00. Exact commands for each OS are on this page.

Is CVE-2026-26378 being exploited?

CVE-2026-26378 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-26378 affect?

CVE-2026-26378 affects koha. Severity is medium (CVSS 5.4). Cross Site Scripting vulnerability in Koha 25.11 and before allows a remote attacker to execute arbitrary code via file upload function in Invoice features

How urgent is CVE-2026-26378?

Priority 30/100. Public exploit reference

Related CVEs

CVE-2026-26379 MEDIUM 6.5 UPGRADE Koha versions up to 25.11 contain a Server-Side Request Forgery (SSRF) vulnerability via the Z39.50/SRU server
CVE-2026-50767 MEDIUM 5.4 UPGRADE A stored cross-site scripting (XSS) vulnerability in the item type administration page of Koha Library Managem
CVE-2026-50766 MEDIUM 5.4 UPGRADE A stored cross-site scripting (XSS) vulnerability in the OPAC item detail page of Koha Library Management Syst
CVE-2026-50765 MEDIUM 6.1 UPGRADE A stored cross-site scripting (XSS) vulnerability in the patron restriction type administration page of Koha L

References

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