CVE-2026-57178: social-auth-core: VK App backend accepts unsigned callback data when auth_key is missing
Vulnerability summary
CVE-2026-57178 is a high (CVSS 7.4) Improper Authentication vulnerability in python-social-auth social-core. EPSS estimates a 0.16% chance of exploitation in the next 30 days, higher than 5.2% of scored vulnerabilities.
Severe, CVSS 7.4 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Timeline
- 24-09-2026PublishedVulnerability first disclosed.
- 28-09-2026Last modifiedVulnerability information updated.
Description
Python Social Auth is a social authentication/registration mechanism. Prior to version 5.0.0, the `vk-app` backend accepted VK application callback data without verifying the callback signature when the `auth_key` parameter was omitted. Applications using this backend could treat unsigned attacker-controlled data as a verified VK identity. An attacker could choose callback fields such as `viewer_id`, `access_token`, `api_id`, and `api_result`, potentially allowing authentication as an arbitrary VK user ID. The issue affects only applications using the `vk-app` backend. The issue has been fixed in version 5.0.0 by requiring `auth_key` to be present and valid before callback data is trusted.
CVSS metrics
6 scores · 6 sources · 1 version- OSV · PypiEcosystem advisory · calculated7.4HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- OSV · UbuntuEcosystem advisory · calculated7.4HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- OSV · DebianEcosystem advisory · calculated7.4HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- NVDNIST7.4HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
- OSV · ChainguardEcosystem advisory · calculated7.4HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
EPSS trend
Probability
0.16%
Chance of exploitation in the next 30 days
Percentile
5%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.16% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-287Improper AuthenticationWhen an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
- CWE-347Improper Verification of Cryptographic SignatureThe product does not verify, or incorrectly verifies, the cryptographic signature for data.
Affected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu11 products
- python2.7All versions (No fix recorded)
- python3.10All versions (No fix recorded)
- python3.11All versions (No fix recorded)
- python3.12All versions (No fix recorded)
- python3.14All versions (No fix recorded)
Chainguard1 product
- awx< 24.6.1-r59 | All versions (No fix recorded)
Debian1 product
- social-auth-coreAll versions (No fix recorded) | < 5.0.2-1
PyPI1 product
- social-auth-core< 5.0.0
Python-social-auth1 product
- social-core< 5.0.0
5 vendors · 15 products
References
12 links- github.com/python-social-auth/social-core/security/advisories/GHSA-3c93-f73f-qc9hX Refsource CONFIRMWEBAdvisory
