How severe is CVE-2020-11503?

CVE-2020-11503 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-2020-11503 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (70th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-11503?

CVE-2020-11503 primarily affects Sophos Sfos. In total, 13 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-11503?

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-2020-11503 published?

CVE-2020-11503 was published on 2020-06-18 and last updated on 2026-06-17.

CVE-2020-11503

CVE-2020-11503 is a critical-severity vulnerability in Sophos Sfos with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-787.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 1% (70th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-787
Affected product: Sophos Sfos
Published: 2020-06-18
Last modified: 2026-06-17

Description

A heap-based buffer overflow in the awarrensmtp component of Sophos XG Firewall v17.5 MR11 and older potentially allows an attacker to run arbitrary code remotely.

Frequently asked questions

What is CVE-2020-11503?: A heap-based buffer overflow in the awarrensmtp component of Sophos XG Firewall v17.5 MR11 and older potentially allows an attacker to run arbitrary code remotely.
How severe is CVE-2020-11503?: CVE-2020-11503 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-2020-11503 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (70th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-11503?: CVE-2020-11503 primarily affects Sophos Sfos. In total, 13 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-11503?: 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-2020-11503 published?: CVE-2020-11503 was published on 2020-06-18 and last updated on 2026-06-17.

References

https://community.sophos.com/b/security-blog/posts/advisory-potential-rce-through-heap-overflow-in-awarrensmtp-cve-2020-11503

Affected products (13)

cpe:2.3:o:sophos:sfos:*:*:*:*:*:*:*:*
cpe:2.3:o:sophos:sfos:17.5:-:*:*:*:*:*:*
cpe:2.3:o:sophos:sfos:17.5:maintenance_release1:*:*:*:*:*:*
cpe:2.3:o:sophos:sfos:17.5:maintenance_release10:*:*:*:*:*:*
cpe:2.3:o:sophos:sfos:17.5:maintenance_release11:*:*:*:*:*:*
cpe:2.3:o:sophos:sfos:17.5:maintenance_release2:*:*:*:*:*:*
cpe:2.3:o:sophos:sfos:17.5:maintenance_release3:*:*:*:*:*:*
cpe:2.3:o:sophos:sfos:17.5:maintenance_release4:*:*:*:*:*:*
cpe:2.3:o:sophos:sfos:17.5:maintenance_release5:*:*:*:*:*:*
cpe:2.3:o:sophos:sfos:17.5:maintenance_release6:*:*:*:*:*:*
cpe:2.3:o:sophos:sfos:17.5:maintenance_release7:*:*:*:*:*:*
cpe:2.3:o:sophos:sfos:17.5:maintenance_release8:*:*:*:*:*:*
cpe:2.3:o:sophos:sfos:17.5:maintenance_release9:*:*:*:*:*:*

More vulnerabilities in Sophos Sfos

CVE-2022-1040 — Critical (CVSS 9.8): An authentication bypass vulnerability in the User Portal and Webadmin allows a remote attacker to execute code in…
CVE-2020-12271 — Critical (CVSS 9.8): A SQL injection issue was found in SFOS 17.0, 17.1, 17.5, and 18.0 before 2020-04-25 on Sophos XG Firewall devices, as…
CVE-2018-16117 — High (CVSS 8.8): A shell escape vulnerability in /webconsole/Controller in Admin Portal of Sophos XG firewall 17.0.8 MR-8 allow remote…
CVE-2018-16116 — High (CVSS 8.8): SQL injection vulnerability in AccountStatus.jsp in Admin Portal of Sophos XG firewall 17.0.8 MR-8 allow remote…
CVE-2018-16118 — High (CVSS 8.1): A shell escape vulnerability in /webconsole/APIController in the API Configuration component of Sophos XG firewall…
CVE-2017-18014 — Medium (CVSS 6.1): An NC-25986 issue was discovered in the Logging subsystem of Sophos XG Firewall with SFOS before 17.0.3 MR3. An…

All CVEs affecting Sophos Sfos →

Other CWE-787 (Out-of-bounds Write) vulnerabilities

CVE-2026-42369 — Critical (CVSS 10.0): GV-VMS V20 is a Video Monitoring Software used to gather the feeds of many surveillance cameras and manage other…
CVE-2026-4746 — Critical (CVSS 10.0): Out-of-bounds Write vulnerability in timeplus-io proton (base/poco/Foundation/src‎ modules). This vulnerability is…
CVE-2025-43300 — Critical (CVSS 10.0): An out-of-bounds write issue was addressed with improved bounds checking. This issue is fixed in iOS 15.8.5 and iPadOS…
CVE-2025-24201 — Critical (CVSS 10.0): An out-of-bounds write issue was addressed with improved checks to prevent unauthorized actions. This issue is fixed in…
CVE-2024-42479 — Critical (CVSS 10.0): llama.cpp provides LLM inference in C/C++. The unsafe `data` pointer member in the `rpc_tensor` structure can cause…
CVE-2024-39791 — Critical (CVSS 10.0): Stack-based buffer overflow vulnerabilities affecting Vonets industrial wifi bridge relays and wifi bridge…

Browse all CWE-787 (Out-of-bounds Write) vulnerabilities →