How severe is CVE-2026-55490?

CVE-2026-55490 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-55490 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-55490?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-55490 published?

CVE-2026-55490 was published on 2026-07-07 and last updated on 2026-07-08.

CVE-2026-55490

CVE-2026-55490 is a medium-severity vulnerability with a CVSS 3.x base score of 6.5. 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-191.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 1% (47th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-191
Published: 2026-07-07
Last modified: 2026-07-08

Description

OpenWrt is a Linux operating system targeting embedded devices. Before v25.12.5, an integer underflow in handle_send_a() of the Emergency Access Daemon allows any unauthenticated attacker on the local network to crash the daemon by sending a single crafted UDP packet. The message length underflows before a bounds check and is then passed to memcpy as a very large size. This issue is fixed v25.12.5.

Frequently asked questions

What is CVE-2026-55490?: OpenWrt is a Linux operating system targeting embedded devices. Before v25.12.5, an integer underflow in handle_send_a() of the Emergency Access Daemon allows any unauthenticated attacker on the local network to crash the daemon by sending a single crafted UDP packet. The message length underflows before a bounds check and is then passed to memcpy as a very large size. This issue is fixed v25.12.5.
How severe is CVE-2026-55490?: CVE-2026-55490 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-55490 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-55490?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-55490 published?: CVE-2026-55490 was published on 2026-07-07 and last updated on 2026-07-08.

References

Other CWE-191 (Integer Underflow) vulnerabilities

CVE-2007-0063 — Critical (CVSS 10.0): Integer underflow in the DHCP server in EMC VMware Workstation before 5.5.5 Build 56455 and 6.x before 6.0.1 Build…
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CVE-2026-37534 — Critical (CVSS 9.8): Integer underflow vulnerability in Open-SAE-J1939 thru commit b6caf884df46435e539b1ecbf92b6c29b345bdfe (2025-11-30) in…
CVE-2025-52471 — Critical (CVSS 9.8): ESF-IDF is the Espressif Internet of Things (IOT) Development Framework. An integer underflow vulnerability has been…
CVE-2025-29909 — Critical (CVSS 9.8): CryptoLib provides a software-only solution using the CCSDS Space Data Link Security Protocol - Extended Procedures…
CVE-2024-47606 — Critical (CVSS 9.8): GStreamer is a library for constructing graphs of media-handling components. An integer underflow has been detected in…

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