Unauthenticated site takeover via pager deserialization
Published Oct 18, 2025 · Updated Oct 18, 2025
PHP object injection in Dan Coulter Flickr Gallery 1.5.2 and earlier allows remote attackers to create backdoors via a POST request. The ajax_pagination() function in flickr-gallery.php calls unserialize() on the unsanitized pager POST value after stripslashes(), instantiating attacker-controlled PHP objects. No authentication is required; observed attacks used the WP_Theme class to fetch and save a remote PHP backdoor at an attacker-chosen path, enabling site takeover.
Summary
What happened
PHP object injection in Dan Coulter Flickr Gallery 1.5.2 and earlier allows remote attackers to create backdoors via a POST request. The ajax_pagination() function in flickr-gallery.php calls unserialize() on the unsanitized pager POST value after stripslashes(), instantiating attacker-controlled PHP objects. No authentication is required; observed attacks used the WP_Theme class to fetch and save a remote PHP backdoor at an attacker-chosen path, enabling site takeover.
The record
- CVE
- CVE-2017-20207
- Published
- Oct 18, 2025
- Updated
- Oct 18, 2025
- Vendor
- Dan Coulter
- Product
- Flickr Gallery
- Classifications
- CWE-502, T1505.003, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Oct 18, 2025CVE publishedPublication date reported by the CVE source.
- Oct 18, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=* <1.5.3
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Flickr Gallery pager object-injection proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Reported exploitation
- Wordfence-observed Flickr Gallery backdoor exploitationreported exploitation
Technologies
Your stack
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Your stack
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