CVE-2026-77470
HIGH 8.3Lychee is a free, open-source photo-management tool. Prior to 7.7.1, the Supporter or Pro webshop POST /api/v2/Shop/Checkout/Process flow accepts an unrestricted additional_data array and CheckoutService::preparePurchaseParameters() merges it after server-computed purchase parameters. Because later string keys overwrite earlier keys, an unauthenticated buyer can replace amount, currency, returnUrl, cancelUrl, or transactionId before CheckoutService::processPayment() passes the parameters to a non-PayPal Omnipay gateway. An attacker can therefore make a gateway accept a successful payment for an attacker-selected amount and obtain auto-fulfilled goods while underpaying the merchant. The issue requires an enabled webshop, a purchasable item, and an affected Omnipay gateway. This issue is fixed in version 7.7.1.
Severe if exploited (CVSS 8.3), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.5%chance of exploitation in 30 days · 39th percentile
Impact if exploited
8.3CVSS 4.0 · HIGH
- ConfidentialityLow
- IntegrityHigh
- AvailabilityNone
What an attacker needs
- ✓Access: Reachable over the network — no local access needed
- ✓Privileges: No account or privileges required
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
- ⚠Requirements: Specific conditions must be present
✓ lowers the bar for an attacker · ⚠ raises it
Proof of concept
No public PoC is currently catalogued.
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Data snapshot:
Weakness (CWE)
- CWE-20: : Improper Input Validation
- CWE-472: : External Control of Assumed-Immutable Web Parameter
- CWE-915: : Improperly Controlled Modification of Dynamically-Determined Object Attributes
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N
References and research data (JSON)
All CVSS metrics
- HIGH 8.3 v4.0 · CNA Primary
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N - HIGH 8.3 v4.0 · NVD Secondary
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
References
Exploit-tagged references (not proof of a PoC)
- https://github.com/LycheeOrg/Lychee/security/advisories/GHSA-476v-jr53-8rxc CVE record · GitHub_M · Updated 2026-10-15T16:36:09.597Z
CVE record · CISA-ADP · Updated 2026-10-15T18:30:17.464Z
NVD · CVE-2026-77470 · Updated 2026-10-15T21:08:49.703
Advisories
- https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-102196 EUVD · EUVD-2026-102196
Technical & other
- https://github.com/LycheeOrg/Lychee/pull/4514 CVE record · GitHub_M · Updated 2026-10-15T16:36:09.597Z
NVD · CVE-2026-77470 · Updated 2026-10-15T21:08:49.703 - https://github.com/LycheeOrg/Lychee/commit/24e6e11f1da131ed20b192d7d7b7ca9084451a2f CVE record · GitHub_M · Updated 2026-10-15T16:36:09.597Z
NVD · CVE-2026-77470 · Updated 2026-10-15T21:08:49.703 - https://github.com/LycheeOrg/Lychee/releases/tag/v7.7.1 CVE record · GitHub_M · Updated 2026-10-15T16:36:09.597Z
NVD · CVE-2026-77470 · Updated 2026-10-15T21:08:49.703