How severe is CVE-2026-77220?

CVE-2026-77220 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.

Is CVE-2026-77220 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-77220?

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

When was CVE-2026-77220 published?

CVE-2026-77220 was published on 2026-08-21.

CVE-2026-77220

CVE-2026-77220 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-825.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v4: 7.1
EPSS exploit prediction: 0% (15th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-825
Published: 2026-08-21
Last modified: 2026-08-21

Description

PDFio before 1.6.5 contains a dangling pointer vulnerability in the dictionary string-formatting function that stores a pointer to a stack-local buffer in the document dictionary without copying the string value. In multi-threaded or pooled-request environments, attackers or concurrent users can trigger stack memory reuse across requests, causing cross-tenant document content corruption by silently overwriting one caller's dictionary string values with another caller's data.

Frequently asked questions

What is CVE-2026-77220?: PDFio before 1.6.5 contains a dangling pointer vulnerability in the dictionary string-formatting function that stores a pointer to a stack-local buffer in the document dictionary without copying the string value. In multi-threaded or pooled-request environments, attackers or concurrent users can trigger stack memory reuse across requests, causing cross-tenant document content corruption by silently overwriting one caller's dictionary string values with another caller's data.
How severe is CVE-2026-77220?: CVE-2026-77220 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability none.
Is CVE-2026-77220 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (15th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-77220?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-77220 published?: CVE-2026-77220 was published on 2026-08-21.

References

Other CWE-825 vulnerabilities

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CVE-2026-17523 — High (CVSS 7.8): A flaw was found in the Linux kernel in net/can/bcm.c in can: bcm, where an unprivileged local user can exploit this…
CVE-2026-46176 — High (CVSS 7.8): In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Fix error path fall-through in…
CVE-2026-34001 — High (CVSS 7.8): A flaw was found in the X.Org X server. This use-after-free vulnerability occurs in the XSYNC fence triggering logic,…
CVE-2026-8854 — High (CVSS 7.5): IBM HTTP Server 8.5, and 9.0 is vulnerable to denial of service via the optional module mod_mem_cache.
CVE-2025-49795 — High (CVSS 7.5): A NULL pointer dereference vulnerability was found in libxml2 when processing XPath XML expressions. This flaw allows…

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