CVE-2020-11945

CVE-2020-11945 is a critical-severity vulnerability in Squid-cache Squid with a CVSS 3.x base score of 9.8. Its EPSS exploit-prediction score of 27% places it in the 98th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-190.

Key facts

Description

An issue was discovered in Squid before 5.0.2. A remote attacker can replay a sniffed Digest Authentication nonce to gain access to resources that are otherwise forbidden. This occurs because the attacker can overflow the nonce reference counter (a short integer). Remote code execution may occur if the pooled token credentials are freed (instead of replayed as valid credentials).

Frequently asked questions

What is CVE-2020-11945?
An issue was discovered in Squid before 5.0.2. A remote attacker can replay a sniffed Digest Authentication nonce to gain access to resources that are otherwise forbidden. This occurs because the attacker can overflow the nonce reference counter (a short integer). Remote code execution may occur if the pooled token credentials are freed (instead of replayed as valid credentials).
How severe is CVE-2020-11945?
CVE-2020-11945 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-11945 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 27% (98th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-11945?
CVE-2020-11945 primarily affects Squid-cache Squid. In total, 11 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-11945?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2020-11945 published?
CVE-2020-11945 was published on 2020-04-23 and last updated on 2026-06-17.

References

Affected products (11)

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Other CWE-190 (Integer Overflow or Wraparound) vulnerabilities

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Threat intelligence

Threat-intel indicators referencing this CVE: