Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
The guzzlehttp/guzzle-services package, versions before 1.5.4, does not safely serialize XML element values that contain the CDATA terminator "]]>". An attacker who can supply such a value to a request parameter with location xml can close the CDATA section early and inject extra XML elements into the outgoing request body. Upgrade to version 1.5.4 or later. Until then, restrict such parameters to values that exclude "]]>" using an enum, pattern, or custom filter.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 5.8 | Medium | 3.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0022, the 12th percentile, on 13 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 14:25 UTC First seen by agentprime
- 31 Oct 2026, 14:25 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-q8r6-5hfw-5jff
- OSV: GHSA-q8r6-5hfw-5jff
- github.com/guzzle/guzzle-services/security/advisories/GHSA-q8r6-5hfw-5jff
- nvd.nist.gov/vuln/detail/CVE-2026-53723
- github.com/FriendsOfPHP/security-advisories/blob/master/guzzlehttp/guzzle-services/CVE-2026-53723.yaml
- github.com/guzzle/guzzle-services