How severe is CVE-2025-5262?

CVE-2025-5262 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2025-5262 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-5262?

CVE-2025-5262 primarily affects Mozilla Thunderbird. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-5262?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2025-5262 have an EU (EUVD) identifier?

Yes. CVE-2025-5262 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-25234.

When was CVE-2025-5262 published?

CVE-2025-5262 was published on 2025-05-27 and last updated on 2026-06-17.

CVE-2025-5262

CVE-2025-5262 is a high-severity vulnerability in Mozilla Thunderbird with a CVSS 3.x base score of 7.5. 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-415.

Key facts

Severity: High (CVSS 3.x base score 7.5)
EPSS exploit prediction: 0% (30th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-25234
Weakness: CWE-415
Affected product: Mozilla Thunderbird
Published: 2025-05-27
Last modified: 2026-06-17

Description

A double-free could have occurred in `vpx_codec_enc_init_multi` after a failed allocation when initializing the encoder for WebRTC. This could have caused memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 139 and Thunderbird < 128.11.

Frequently asked questions

What is CVE-2025-5262?: A double-free could have occurred in `vpx_codec_enc_init_multi` after a failed allocation when initializing the encoder for WebRTC. This could have caused memory corruption and a potentially exploitable crash. This vulnerability affects Thunderbird < 139 and Thunderbird < 128.11.
How severe is CVE-2025-5262?: CVE-2025-5262 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2025-5262 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-5262?: CVE-2025-5262 primarily affects Mozilla Thunderbird. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-5262?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2025-5262 have an EU (EUVD) identifier?: Yes. CVE-2025-5262 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-25234.
When was CVE-2025-5262 published?: CVE-2025-5262 was published on 2025-05-27 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*

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