CVE-2026-109426
HIGH 8.2Telegram-Stremio through 5.1.0 contains an insecure storage vulnerability that allows attackers with access to the MongoDB database, backups, or logs to recover the operator's authenticated Telegram session string, which is protected only by a keyless, reversible encoding transform rather than actual encryption. Attackers can round-trip the stored value through the repository's own decode_string function with no secret key to obtain a fully authenticated Telegram session, granting complete control of the operator's Telegram account even when two-step verification is enabled.
Severe if exploited (CVSS 8.2), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.1%chance of exploitation in 30 days · 1st percentile
Impact if exploited
8.2CVSS 4.0 · HIGH
- ConfidentialityHigh
- IntegrityNone
- 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-312: Cleartext Storage of Sensitive Information
CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
References and research data (JSON)
All CVSS metrics
- HIGH 8.2 v4.0 · CNA Primary
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N - HIGH 7.5 v3.1 · CNA Primary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N - HIGH 8.2 v4.0 · NVD Secondary
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/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 - HIGH 7.5 v3.1 · NVD Secondary
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
References
Advisories
- https://www.vulncheck.com/advisories/telegram-stremio-insecure-session-storage-via-encode-string CVE record · VulnCheck · Updated 2026-10-12T20:34:18.671Z
NVD · CVE-2026-109426 · Updated 2026-10-16T19:18:44.867 - https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-97910 EUVD · EUVD-2026-97910
Technical & other
- https://gist.github.com/mansurmavlankulov/489554cad7b38e07b9651c217f00fffb CVE record · VulnCheck · Updated 2026-10-12T20:34:18.671Z
NVD · CVE-2026-109426 · Updated 2026-10-16T19:18:44.867