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Fencer Vulns
high 8.1

CVE-2026-97055 json

SigNoz before 0.143.0 Authentication Bypass via Empty JWT Secret

published 2026-09-24 46 d ago modified 2026-09-24 45 d ago also EUVD-2026-85774

cvss
8.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 45%
public exploits
0
none known

Summary

SigNoz from v0.8.0 before v0.143.0 defaults the JWT tokenizer signing secret (tokenizer::jwt::secret, set via SIGNOZ_TOKENIZER_JWT_SECRET or the deprecated SIGNOZ_JWT_SECRET) to an empty string, and Config.Validate() does not reject the empty value, so a deployment that does not configure a secret starts up and both signs and verifies session tokens with an empty HMAC key. Because the JWT tokenizer was the default provider, any such deployment is affected. An unauthenticated attacker who knows the ID of an existing user can forge a valid session token for that user — including an administrator — by signing the id, orgId and email claims with an empty key; the organization ID (and whether an email is registered) can be obtained without authentication from /api/v2/sessions/context. A forged refresh token can be exchanged at /api/v2/sessions/rotate for a new token pair and cannot be revoked, so it remains usable for its full lifetime (30 days by default). Fixed in v0.143.0, which requires a JWT secret when the jwt provider is selected and changes the default provider to opaque.

Patch / fix

  • SigNoz signoz 0.143.0

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
45 d ago

Exploit prediction

0.53% chance of exploitation in the next 30 days, higher than 45% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/SigNoz/signoz/security/advisories/GHSA-c26w-g4j8-39m2 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 9.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CNA 3.1 8.1 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 4.0 9.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/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

Affected products

  • SigNoz signoz

Classification

Weakness
  • CWE-1188 Initialization of a Resource with an Insecure Default

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.